From 80152b333ca5d856dcf09f5ca10a9ffd80ba117f Mon Sep 17 00:00:00 2001
From: alecpl <alec@alec.pl>
Date: Wed, 07 Sep 2011 07:07:03 -0400
Subject: [PATCH] - Rewritten messages caching (merged devel-mcache branch):   Indexes are stored in a separate table, so there's no need to store all messages in a folder   Added threads data caching   Flags are stored separately, so flag change doesn't cause DELETE+INSERT, just UPDATE - Partial QRESYNC support - Improved FETCH response handling - Improvements in response tokenization method

---
 CHANGELOG                              |    7 
 program/include/main.inc               |   14 
 program/include/rcube_mime_struct.php  |   88 -
 program/steps/mail/show.inc            |    2 
 SQL/mysql.update.sql                   |   42 
 program/include/rcube_message.php      |    8 
 SQL/sqlite.initial.sql                 |   87 
 program/include/rcube_imap.php         | 1207 ++++++-------------
 SQL/sqlite.update.sql                  |   41 
 program/include/rcube_imap_cache.php   |  907 +++++++++++++++
 program/steps/mail/func.inc            |    2 
 SQL/postgres.update.sql                |   43 
 SQL/postgres.initial.sql               |   84 
 SQL/mysql.initial.sql                  |   76 
 SQL/mssql.initial.sql                  |  144 +
 program/include/rcube_imap_generic.php |  595 ++++++---
 SQL/mssql.upgrade.sql                  |   96 +
 17 files changed, 2,178 insertions(+), 1,265 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index f959c71..7a89731 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,13 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Rewritten messages caching:
+  Indexes are stored in a separate table, so there's no need to store all messages in a folder
+  Added threads data caching
+  Flags are stored separately, so flag change doesn't cause DELETE+INSERT, just UPDATE
+- Partial QRESYNC support
+- Improved FETCH response handling
+- Improvements in response tokenization method
 - Use 'From' and 'To' labels instead of 'Sender' and 'Recipient'
 - Fix username case-insensitivity issue in MySQL (#1488021)
 - Addressbook Saved Searches
diff --git a/SQL/mssql.initial.sql b/SQL/mssql.initial.sql
index 8e103eb..eb5f20b 100644
--- a/SQL/mssql.initial.sql
+++ b/SQL/mssql.initial.sql
@@ -7,6 +7,37 @@
 ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
 GO
 
+CREATE TABLE [dbo].[cache_index] (
+	[user_id] [int] NOT NULL ,
+	[mailbox] [varchar] (128) COLLATE Latin1_General_CI_AI NOT NULL ,
+	[changed] [datetime] NOT NULL ,
+	[data] [text] COLLATE Latin1_General_CI_AI NOT NULL 
+) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
+GO
+
+CREATE TABLE [dbo].[cache_thread] (
+	[user_id] [int] NOT NULL ,
+	[mailbox] [varchar] (128) COLLATE Latin1_General_CI_AI NOT NULL ,
+	[changed] [datetime] NOT NULL ,
+	[data] [text] COLLATE Latin1_General_CI_AI NOT NULL 
+) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
+GO
+
+CREATE TABLE [dbo].[cache_messages] (
+	[user_id] [int] NOT NULL ,
+	[mailbox] [varchar] (128) COLLATE Latin1_General_CI_AI NOT NULL ,
+	[uid] [int] NOT NULL ,
+	[changed] [datetime] NOT NULL ,
+	[data] [text] COLLATE Latin1_General_CI_AI NOT NULL 
+	[seen] [char](1) NOT NULL ,
+	[deleted] [char](1) NOT NULL ,
+	[answered] [char](1) NOT NULL ,
+	[forwarded] [char](1) NOT NULL ,
+	[flagged] [char](1) NOT NULL ,
+	[mdnsent] [char](1) NOT NULL ,
+) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
+GO
+
 CREATE TABLE [dbo].[contacts] (
 	[contact_id] [int] IDENTITY (1, 1) NOT NULL ,
 	[user_id] [int] NOT NULL ,
@@ -50,25 +81,6 @@
 	[bcc] [varchar] (128) COLLATE Latin1_General_CI_AI NOT NULL ,
 	[signature] [text] COLLATE Latin1_General_CI_AI NULL, 
 	[html_signature] [char] (1) COLLATE Latin1_General_CI_AI NOT NULL
-) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
-GO
-
-CREATE TABLE [dbo].[messages] (
-	[message_id] [int] IDENTITY (1, 1) NOT NULL ,
-	[user_id] [int] NOT NULL ,
-	[del] [tinyint] NOT NULL ,
-	[cache_key] [varchar] (128) COLLATE Latin1_General_CI_AI NOT NULL ,
-	[created] [datetime] NOT NULL ,
-	[idx] [int] NOT NULL ,
-	[uid] [int] NOT NULL ,
-	[subject] [varchar] (255) COLLATE Latin1_General_CI_AI NOT NULL ,
-	[from] [varchar] (255) COLLATE Latin1_General_CI_AI NOT NULL ,
-	[to] [varchar] (255) COLLATE Latin1_General_CI_AI NOT NULL ,
-	[cc] [varchar] (255) COLLATE Latin1_General_CI_AI NOT NULL ,
-	[date] [datetime] NOT NULL ,
-	[size] [int] NOT NULL ,
-	[headers] [text] COLLATE Latin1_General_CI_AI NOT NULL ,
-	[structure] [text] COLLATE Latin1_General_CI_AI NULL 
 ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
 GO
 
@@ -116,6 +128,27 @@
 	)  ON [PRIMARY] 
 GO
 
+ALTER TABLE [dbo].[cache_index] WITH NOCHECK ADD 
+	 PRIMARY KEY CLUSTERED 
+	(
+		[user_id],[mailbox]
+	) ON [PRIMARY] 
+GO
+
+ALTER TABLE [dbo].[cache_thread] WITH NOCHECK ADD 
+	 PRIMARY KEY CLUSTERED 
+	(
+		[user_id],[mailbox]
+	) ON [PRIMARY] 
+GO
+
+ALTER TABLE [dbo].[cache_messages] WITH NOCHECK ADD 
+	 PRIMARY KEY CLUSTERED 
+	(
+		[user_id],[mailbox],[uid]
+	) ON [PRIMARY] 
+GO
+
 ALTER TABLE [dbo].[contacts] WITH NOCHECK ADD 
 	CONSTRAINT [PK_contacts_contact_id] PRIMARY KEY  CLUSTERED 
 	(
@@ -141,13 +174,6 @@
 	 PRIMARY KEY  CLUSTERED 
 	(
 		[identity_id]
-	)  ON [PRIMARY] 
-GO
-
-ALTER TABLE [dbo].[messages] WITH NOCHECK ADD 
-	 PRIMARY KEY  CLUSTERED 
-	(
-		[message_id]
 	)  ON [PRIMARY] 
 GO
 
@@ -185,6 +211,33 @@
 GO
 
 CREATE  INDEX [IX_cache_created] ON [dbo].[cache]([created]) ON [PRIMARY]
+GO
+
+ALTER TABLE [dbo].[cache_index] ADD 
+	CONSTRAINT [DF_cache_index_changed] DEFAULT (getdate()) FOR [changed]
+GO
+
+CREATE  INDEX [IX_cache_index_user_id] ON [dbo].[cache_index]([user_id]) ON [PRIMARY]
+GO
+
+ALTER TABLE [dbo].[cache_thread] ADD 
+	CONSTRAINT [DF_cache_thread_changed] DEFAULT (getdate()) FOR [changed]
+GO
+
+CREATE  INDEX [IX_cache_thread_user_id] ON [dbo].[cache_thread]([user_id]) ON [PRIMARY]
+GO
+
+ALTER TABLE [dbo].[cache_messages] ADD 
+	CONSTRAINT [DF_cache_messages_changed] DEFAULT (getdate()) FOR [changed]
+	CONSTRAINT [DF_cache_messages_seen] DEFAULT (0) FOR [seen],
+	CONSTRAINT [DF_cache_messages_deleted] DEFAULT (0) FOR [deleted],
+	CONSTRAINT [DF_cache_messages_answered] DEFAULT (0) FOR [answered],
+	CONSTRAINT [DF_cache_messages_forwarded] DEFAULT (0) FOR [forwarded],
+	CONSTRAINT [DF_cache_messages_flagged] DEFAULT (0) FOR [flagged],
+	CONSTRAINT [DF_cache_messages_mdnsent] DEFAULT (0) FOR [mdnsent],
+GO
+
+CREATE  INDEX [IX_cache_messages_user_id] ON [dbo].[cache_messages]([user_id]) ON [PRIMARY]
 GO
 
 ALTER TABLE [dbo].[contacts] ADD 
@@ -236,33 +289,6 @@
 GO
 
 CREATE  INDEX [IX_identities_user_id] ON [dbo].[identities]([user_id]) ON [PRIMARY]
-GO
-
-ALTER TABLE [dbo].[messages] ADD 
-	CONSTRAINT [DF_messages_user_id] DEFAULT (0) FOR [user_id],
-	CONSTRAINT [DF_messages_del] DEFAULT (0) FOR [del],
-	CONSTRAINT [DF_messages_cache_key] DEFAULT ('') FOR [cache_key],
-	CONSTRAINT [DF_messages_created] DEFAULT (getdate()) FOR [created],
-	CONSTRAINT [DF_messages_idx] DEFAULT (0) FOR [idx],
-	CONSTRAINT [DF_messages_uid] DEFAULT (0) FOR [uid],
-	CONSTRAINT [DF_messages_subject] DEFAULT ('') FOR [subject],
-	CONSTRAINT [DF_messages_from] DEFAULT ('') FOR [from],
-	CONSTRAINT [DF_messages_to] DEFAULT ('') FOR [to],
-	CONSTRAINT [DF_messages_cc] DEFAULT ('') FOR [cc],
-	CONSTRAINT [DF_messages_date] DEFAULT (getdate()) FOR [date],
-	CONSTRAINT [DF_messages_size] DEFAULT (0) FOR [size]
-GO
-
-CREATE  INDEX [IX_messages_user_id] ON [dbo].[messages]([user_id]) ON [PRIMARY]
-GO
-
-CREATE  INDEX [IX_messages_cache_key] ON [dbo].[messages]([cache_key]) ON [PRIMARY]
-GO
-
-CREATE  INDEX [IX_messages_uid] ON [dbo].[messages]([uid]) ON [PRIMARY]
-GO
-
-CREATE  INDEX [IX_messages_created] ON [dbo].[messages]([created]) ON [PRIMARY]
 GO
 
 ALTER TABLE [dbo].[session] ADD 
@@ -318,7 +344,17 @@
     ON DELETE CASCADE ON UPDATE CASCADE
 GO
 
-ALTER TABLE [dbo].[messages] ADD CONSTRAINT [FK_messages_user_id]
+ALTER TABLE [dbo].[cache_index] ADD CONSTRAINT [FK_cache_index_user_id]
+    FOREIGN KEY ([user_id]) REFERENCES [dbo].[users] ([user_id])
+    ON DELETE CASCADE ON UPDATE CASCADE
+GO
+
+ALTER TABLE [dbo].[cache_thread] ADD CONSTRAINT [FK_cache_thread_user_id]
+    FOREIGN KEY ([user_id]) REFERENCES [dbo].[users] ([user_id])
+    ON DELETE CASCADE ON UPDATE CASCADE
+GO
+
+ALTER TABLE [dbo].[cache_messages] ADD CONSTRAINT [FK_cache_messages_user_id]
     FOREIGN KEY ([user_id]) REFERENCES [dbo].[users] ([user_id])
     ON DELETE CASCADE ON UPDATE CASCADE
 GO
diff --git a/SQL/mssql.upgrade.sql b/SQL/mssql.upgrade.sql
index 258b1d7..29440f9 100644
--- a/SQL/mssql.upgrade.sql
+++ b/SQL/mssql.upgrade.sql
@@ -151,3 +151,99 @@
     ON DELETE CASCADE ON UPDATE CASCADE
 GO
 
+DROP TABLE [dbo].[messages]
+GO
+CREATE TABLE [dbo].[cache_index] (
+	[user_id] [int] NOT NULL ,
+	[mailbox] [varchar] (128) COLLATE Latin1_General_CI_AI NOT NULL ,
+	[changed] [datetime] NOT NULL ,
+	[data] [text] COLLATE Latin1_General_CI_AI NOT NULL 
+) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
+GO
+
+CREATE TABLE [dbo].[cache_thread] (
+	[user_id] [int] NOT NULL ,
+	[mailbox] [varchar] (128) COLLATE Latin1_General_CI_AI NOT NULL ,
+	[changed] [datetime] NOT NULL ,
+	[data] [text] COLLATE Latin1_General_CI_AI NOT NULL 
+) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
+GO
+
+CREATE TABLE [dbo].[cache_messages] (
+	[user_id] [int] NOT NULL ,
+	[mailbox] [varchar] (128) COLLATE Latin1_General_CI_AI NOT NULL ,
+	[uid] [int] NOT NULL ,
+	[changed] [datetime] NOT NULL ,
+	[data] [text] COLLATE Latin1_General_CI_AI NOT NULL 
+	[seen] [char](1) NOT NULL ,
+	[deleted] [char](1) NOT NULL ,
+	[answered] [char](1) NOT NULL ,
+	[forwarded] [char](1) NOT NULL ,
+	[flagged] [char](1) NOT NULL ,
+	[mdnsent] [char](1) NOT NULL ,
+) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
+GO
+
+ALTER TABLE [dbo].[cache_index] WITH NOCHECK ADD 
+	 PRIMARY KEY CLUSTERED 
+	(
+		[user_id],[mailbox]
+	) ON [PRIMARY] 
+GO
+
+ALTER TABLE [dbo].[cache_thread] WITH NOCHECK ADD 
+	 PRIMARY KEY CLUSTERED 
+	(
+		[user_id],[mailbox]
+	) ON [PRIMARY] 
+GO
+
+ALTER TABLE [dbo].[cache_messages] WITH NOCHECK ADD 
+	 PRIMARY KEY CLUSTERED 
+	(
+		[user_id],[mailbox],[uid]
+	) ON [PRIMARY] 
+GO
+
+ALTER TABLE [dbo].[cache_index] ADD 
+	CONSTRAINT [DF_cache_index_changed] DEFAULT (getdate()) FOR [changed]
+GO
+
+CREATE  INDEX [IX_cache_index_user_id] ON [dbo].[cache_index]([user_id]) ON [PRIMARY]
+GO
+
+ALTER TABLE [dbo].[cache_thread] ADD 
+	CONSTRAINT [DF_cache_thread_changed] DEFAULT (getdate()) FOR [changed]
+GO
+
+CREATE  INDEX [IX_cache_thread_user_id] ON [dbo].[cache_thread]([user_id]) ON [PRIMARY]
+GO
+
+ALTER TABLE [dbo].[cache_messages] ADD 
+	CONSTRAINT [DF_cache_messages_changed] DEFAULT (getdate()) FOR [changed]
+	CONSTRAINT [DF_cache_messages_seen] DEFAULT (0) FOR [seen],
+	CONSTRAINT [DF_cache_messages_deleted] DEFAULT (0) FOR [deleted],
+	CONSTRAINT [DF_cache_messages_answered] DEFAULT (0) FOR [answered],
+	CONSTRAINT [DF_cache_messages_forwarded] DEFAULT (0) FOR [forwarded],
+	CONSTRAINT [DF_cache_messages_flagged] DEFAULT (0) FOR [flagged],
+	CONSTRAINT [DF_cache_messages_mdnsent] DEFAULT (0) FOR [mdnsent],
+GO
+
+CREATE  INDEX [IX_cache_messages_user_id] ON [dbo].[cache_messages]([user_id]) ON [PRIMARY]
+GO
+
+ALTER TABLE [dbo].[cache_index] ADD CONSTRAINT [FK_cache_index_user_id]
+    FOREIGN KEY ([user_id]) REFERENCES [dbo].[users] ([user_id])
+    ON DELETE CASCADE ON UPDATE CASCADE
+GO
+
+ALTER TABLE [dbo].[cache_thread] ADD CONSTRAINT [FK_cache_thread_user_id]
+    FOREIGN KEY ([user_id]) REFERENCES [dbo].[users] ([user_id])
+    ON DELETE CASCADE ON UPDATE CASCADE
+GO
+
+ALTER TABLE [dbo].[cache_messages] ADD CONSTRAINT [FK_cache_messages_user_id]
+    FOREIGN KEY ([user_id]) REFERENCES [dbo].[users] ([user_id])
+    ON DELETE CASCADE ON UPDATE CASCADE
+GO
+
\ No newline at end of file
diff --git a/SQL/mysql.initial.sql b/SQL/mysql.initial.sql
index a50e28c..32b3991 100644
--- a/SQL/mysql.initial.sql
+++ b/SQL/mysql.initial.sql
@@ -33,33 +33,6 @@
 ) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
 
 
--- Table structure for table `messages`
-
-CREATE TABLE `messages` (
- `message_id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
- `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
- `del` tinyint(1) NOT NULL DEFAULT '0',
- `cache_key` varchar(128) /*!40101 CHARACTER SET ascii COLLATE ascii_general_ci */ NOT NULL,
- `created` datetime NOT NULL DEFAULT '1000-01-01 00:00:00',
- `idx` int(11) UNSIGNED NOT NULL DEFAULT '0',
- `uid` int(11) UNSIGNED NOT NULL DEFAULT '0',
- `subject` varchar(255) NOT NULL,
- `from` varchar(255) NOT NULL,
- `to` varchar(255) NOT NULL,
- `cc` varchar(255) NOT NULL,
- `date` datetime NOT NULL DEFAULT '1000-01-01 00:00:00',
- `size` int(11) UNSIGNED NOT NULL DEFAULT '0',
- `headers` text NOT NULL,
- `structure` text,
- PRIMARY KEY(`message_id`),
- CONSTRAINT `user_id_fk_messages` FOREIGN KEY (`user_id`)
-   REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
- INDEX `created_index` (`created`),
- INDEX `index_index` (`user_id`, `cache_key`, `idx`),
- UNIQUE `uniqueness` (`user_id`, `cache_key`, `uid`)
-) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
-
-
 -- Table structure for table `cache`
 
 CREATE TABLE `cache` (
@@ -76,6 +49,55 @@
 ) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
 
 
+-- Table structure for table `cache_index`
+
+CREATE TABLE `cache_index` (
+ `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+ `mailbox` varchar(255) BINARY NOT NULL,
+ `changed` datetime NOT NULL DEFAULT '1000-01-01 00:00:00',
+ `data` longtext NOT NULL,
+ CONSTRAINT `user_id_fk_cache_index` FOREIGN KEY (`user_id`)
+   REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
+ INDEX `changed_index` (`changed`),
+ PRIMARY KEY (`user_id`, `mailbox`)
+) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
+
+
+-- Table structure for table `cache_thread`
+
+CREATE TABLE `cache_thread` (
+ `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+ `mailbox` varchar(255) BINARY NOT NULL,
+ `changed` datetime NOT NULL DEFAULT '1000-01-01 00:00:00',
+ `data` longtext NOT NULL,
+ CONSTRAINT `user_id_fk_cache_thread` FOREIGN KEY (`user_id`)
+   REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
+ INDEX `changed_index` (`changed`),
+ PRIMARY KEY (`user_id`, `mailbox`)
+) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
+
+
+-- Table structure for table `cache_messages`
+
+CREATE TABLE `cache_messages` (
+ `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+ `mailbox` varchar(255) BINARY NOT NULL,
+ `uid` int(11) UNSIGNED NOT NULL DEFAULT '0',
+ `changed` datetime NOT NULL DEFAULT '1000-01-01 00:00:00',
+ `data` longtext NOT NULL,
+ `seen` tinyint(1) NOT NULL DEFAULT '0',
+ `deleted` tinyint(1) NOT NULL DEFAULT '0',
+ `answered` tinyint(1) NOT NULL DEFAULT '0',
+ `forwarded` tinyint(1) NOT NULL DEFAULT '0',
+ `flagged` tinyint(1) NOT NULL DEFAULT '0',
+ `mdnsent` tinyint(1) NOT NULL DEFAULT '0',
+ CONSTRAINT `user_id_fk_cache_messages` FOREIGN KEY (`user_id`)
+   REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
+ INDEX `changed_index` (`changed`),
+ PRIMARY KEY (`user_id`, `mailbox`, `uid`)
+) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
+
+
 -- Table structure for table `contacts`
 
 CREATE TABLE `contacts` (
diff --git a/SQL/mysql.update.sql b/SQL/mysql.update.sql
index 7f8ce61..fee18d6 100644
--- a/SQL/mysql.update.sql
+++ b/SQL/mysql.update.sql
@@ -170,3 +170,45 @@
     REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
   UNIQUE `uniqueness` (`user_id`, `type`, `name`)
 ) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
+
+DROP TABLE `messages`;
+
+CREATE TABLE `cache_index` (
+ `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+ `mailbox` varchar(255) BINARY NOT NULL,
+ `changed` datetime NOT NULL DEFAULT '1000-01-01 00:00:00',
+ `data` longtext NOT NULL,
+ CONSTRAINT `user_id_fk_cache_index` FOREIGN KEY (`user_id`)
+   REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
+ INDEX `changed_index` (`changed`),
+ PRIMARY KEY (`user_id`, `mailbox`)
+) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
+
+CREATE TABLE `cache_thread` (
+ `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+ `mailbox` varchar(255) BINARY NOT NULL,
+ `changed` datetime NOT NULL DEFAULT '1000-01-01 00:00:00',
+ `data` longtext NOT NULL,
+ CONSTRAINT `user_id_fk_cache_thread` FOREIGN KEY (`user_id`)
+   REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
+ INDEX `changed_index` (`changed`),
+ PRIMARY KEY (`user_id`, `mailbox`)
+) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
+
+CREATE TABLE `cache_messages` (
+ `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+ `mailbox` varchar(255) BINARY NOT NULL,
+ `uid` int(11) UNSIGNED NOT NULL DEFAULT '0',
+ `changed` datetime NOT NULL DEFAULT '1000-01-01 00:00:00',
+ `data` longtext NOT NULL,
+ `seen` tinyint(1) NOT NULL DEFAULT '0',
+ `deleted` tinyint(1) NOT NULL DEFAULT '0',
+ `answered` tinyint(1) NOT NULL DEFAULT '0',
+ `forwarded` tinyint(1) NOT NULL DEFAULT '0',
+ `flagged` tinyint(1) NOT NULL DEFAULT '0',
+ `mdnsent` tinyint(1) NOT NULL DEFAULT '0',
+ CONSTRAINT `user_id_fk_cache_messages` FOREIGN KEY (`user_id`)
+   REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
+ INDEX `changed_index` (`changed`),
+ PRIMARY KEY (`user_id`, `mailbox`, `uid`)
+) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
diff --git a/SQL/postgres.initial.sql b/SQL/postgres.initial.sql
index 01221c4..a1864c6 100644
--- a/SQL/postgres.initial.sql
+++ b/SQL/postgres.initial.sql
@@ -67,7 +67,7 @@
 CREATE TABLE identities (
     identity_id integer DEFAULT nextval('identity_ids'::text) PRIMARY KEY,
     user_id integer NOT NULL
-	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+        REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
     changed timestamp with time zone DEFAULT now() NOT NULL,
     del smallint DEFAULT 0 NOT NULL,
     standard smallint DEFAULT 0 NOT NULL,
@@ -178,7 +178,7 @@
 CREATE TABLE "cache" (
     cache_id integer DEFAULT nextval('cache_ids'::text) PRIMARY KEY,
     user_id integer NOT NULL
-	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+    	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
     cache_key varchar(128) DEFAULT '' NOT NULL,
     created timestamp with time zone DEFAULT now() NOT NULL,
     data text NOT NULL
@@ -188,43 +188,59 @@
 CREATE INDEX cache_created_idx ON "cache" (created);
 
 --
--- Sequence "message_ids"
--- Name: message_ids; Type: SEQUENCE; Schema: public; Owner: postgres
+-- Table "cache_index"
+-- Name: cache_index; Type: TABLE; Schema: public; Owner: postgres
 --
 
-CREATE SEQUENCE message_ids
-    INCREMENT BY 1
-    NO MAXVALUE
-    NO MINVALUE
-    CACHE 1;
-
---
--- Table "messages"
--- Name: messages; Type: TABLE; Schema: public; Owner: postgres
---
-
-CREATE TABLE messages (
-    message_id integer DEFAULT nextval('message_ids'::text) PRIMARY KEY,
+CREATE TABLE cache_index (
     user_id integer NOT NULL
-	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
-    del smallint DEFAULT 0 NOT NULL,
-    cache_key varchar(128) DEFAULT '' NOT NULL,
-    created timestamp with time zone DEFAULT now() NOT NULL,
-    idx integer DEFAULT 0 NOT NULL,
-    uid integer DEFAULT 0 NOT NULL,
-    subject varchar(128) DEFAULT '' NOT NULL,
-    "from" varchar(128) DEFAULT '' NOT NULL,
-    "to" varchar(128) DEFAULT '' NOT NULL,
-    cc varchar(128) DEFAULT '' NOT NULL,
-    date timestamp with time zone NOT NULL,
-    size integer DEFAULT 0 NOT NULL,
-    headers text NOT NULL,
-    structure text,
-    CONSTRAINT messages_user_id_key UNIQUE (user_id, cache_key, uid)
+    	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+    mailbox varchar(255) NOT NULL,
+    changed timestamp with time zone DEFAULT now() NOT NULL,
+    data text NOT NULL,
+    PRIMARY KEY (user_id, mailbox)
 );
 
-CREATE INDEX messages_index_idx ON messages (user_id, cache_key, idx);
-CREATE INDEX messages_created_idx ON messages (created);
+CREATE INDEX cache_index_changed_idx ON cache_index (changed);
+
+--
+-- Table "cache_thread"
+-- Name: cache_thread; Type: TABLE; Schema: public; Owner: postgres
+--
+
+CREATE TABLE cache_thread (
+    user_id integer NOT NULL
+    	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+    mailbox varchar(255) NOT NULL,
+    changed timestamp with time zone DEFAULT now() NOT NULL,
+    data text NOT NULL,
+    PRIMARY KEY (user_id, mailbox)
+);
+
+CREATE INDEX cache_thread_changed_idx ON cache_thread (changed);
+
+--
+-- Table "cache_messages"
+-- Name: cache_messages; Type: TABLE; Schema: public; Owner: postgres
+--
+
+CREATE TABLE cache_messages (
+    user_id integer NOT NULL
+    	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+    mailbox varchar(255) NOT NULL,
+    uid integer NOT NULL,
+    changed timestamp with time zone DEFAULT now() NOT NULL,
+    data text NOT NULL,
+    seen smallint NOT NULL DEFAULT 0,
+    deleted smallint NOT NULL DEFAULT 0,
+    answered smallint NOT NULL DEFAULT 0,
+    forwarded smallint NOT NULL DEFAULT 0,
+    flagged smallint NOT NULL DEFAULT 0,
+    mdnsent smallint NOT NULL DEFAULT 0,
+    PRIMARY KEY (user_id, mailbox, uid)
+);
+
+CREATE INDEX cache_messages_changed_idx ON cache_messages (changed);
 
 --
 -- Table "dictionary"
diff --git a/SQL/postgres.update.sql b/SQL/postgres.update.sql
index e316ff5..4bd0400 100644
--- a/SQL/postgres.update.sql
+++ b/SQL/postgres.update.sql
@@ -126,3 +126,46 @@
     data text NOT NULL,
     CONSTRAINT searches_user_id_key UNIQUE (user_id, "type", name)
 );
+
+DROP SEQUENCE messages_ids;
+DROP TABLE messages;
+
+CREATE TABLE cache_index (
+    user_id integer NOT NULL
+    	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+    mailbox varchar(255) NOT NULL,
+    changed timestamp with time zone DEFAULT now() NOT NULL,
+    data text NOT NULL,
+    PRIMARY KEY (user_id, mailbox)
+);
+
+CREATE INDEX cache_index_changed_idx ON cache_index (changed);
+
+CREATE TABLE cache_thread (
+    user_id integer NOT NULL
+    	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+    mailbox varchar(255) NOT NULL,
+    changed timestamp with time zone DEFAULT now() NOT NULL,
+    data text NOT NULL,
+    PRIMARY KEY (user_id, mailbox)
+);
+
+CREATE INDEX cache_thread_changed_idx ON cache_thread (changed);
+
+CREATE TABLE cache_messages (
+    user_id integer NOT NULL
+    	REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+    mailbox varchar(255) NOT NULL,
+    uid integer NOT NULL,
+    changed timestamp with time zone DEFAULT now() NOT NULL,
+    data text NOT NULL,
+    seen smallint NOT NULL DEFAULT 0,
+    deleted smallint NOT NULL DEFAULT 0,
+    answered smallint NOT NULL DEFAULT 0,
+    forwarded smallint NOT NULL DEFAULT 0,
+    flagged smallint NOT NULL DEFAULT 0,
+    mdnsent smallint NOT NULL DEFAULT 0,
+    PRIMARY KEY (user_id, mailbox, uid)
+);
+
+CREATE INDEX cache_messages_changed_idx ON cache_messages (changed);
diff --git a/SQL/sqlite.initial.sql b/SQL/sqlite.initial.sql
index 46ee530..7ec8201 100644
--- a/SQL/sqlite.initial.sql
+++ b/SQL/sqlite.initial.sql
@@ -1,7 +1,7 @@
 -- Roundcube Webmail initial database structure
 
 -- 
--- Table structure for table `cache`
+-- Table structure for table cache
 -- 
 
 CREATE TABLE cache (
@@ -9,7 +9,7 @@
   user_id integer NOT NULL default 0,
   cache_key varchar(128) NOT NULL default '',
   created datetime NOT NULL default '0000-00-00 00:00:00',
-  data longtext NOT NULL
+  data text NOT NULL
 );
 
 CREATE INDEX ix_cache_user_cache_key ON cache(user_id, cache_key);
@@ -121,34 +121,6 @@
 
 -- --------------------------------------------------------
 
--- 
--- Table structure for table messages
--- 
-
-CREATE TABLE messages (
-  message_id integer NOT NULL PRIMARY KEY,
-  user_id integer NOT NULL default '0',
-  del tinyint NOT NULL default '0',
-  cache_key varchar(128) NOT NULL default '',
-  created datetime NOT NULL default '0000-00-00 00:00:00',
-  idx integer NOT NULL default '0',
-  uid integer NOT NULL default '0',
-  subject varchar(255) NOT NULL default '',
-  "from" varchar(255) NOT NULL default '',
-  "to" varchar(255) NOT NULL default '',
-  "cc" varchar(255) NOT NULL default '',
-  "date" datetime NOT NULL default '0000-00-00 00:00:00',
-  size integer NOT NULL default '0',
-  headers text NOT NULL,
-  structure text
-);
-
-CREATE UNIQUE INDEX ix_messages_user_cache_uid ON messages (user_id,cache_key,uid);
-CREATE INDEX ix_messages_index ON messages (user_id,cache_key,idx);
-CREATE INDEX ix_messages_created ON messages (created);
-
--- --------------------------------------------------------
-
 --
 -- Table structure for table dictionary
 --
@@ -176,3 +148,58 @@
 );
 
 CREATE UNIQUE INDEX ix_searches_user_type_name (user_id, type, name);
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table cache_index
+--
+
+CREATE TABLE cache_index (
+    user_id integer NOT NULL,
+    mailbox varchar(255) NOT NULL,
+    changed datetime NOT NULL default '0000-00-00 00:00:00',
+    data text NOT NULL,
+    PRIMARY KEY (user_id, mailbox)
+);
+
+CREATE INDEX ix_cache_index_changed ON cache_index (changed);
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table cache_thread
+--
+
+CREATE TABLE cache_thread (
+    user_id integer NOT NULL,
+    mailbox varchar(255) NOT NULL,
+    changed datetime NOT NULL default '0000-00-00 00:00:00',
+    data text NOT NULL,
+    PRIMARY KEY (user_id, mailbox)
+);
+
+CREATE INDEX ix_cache_thread_changed ON cache_thread (changed);
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table cache_messages
+--
+
+CREATE TABLE cache_messages (
+    user_id integer NOT NULL,
+    mailbox varchar(255) NOT NULL,
+    uid integer NOT NULL,
+    changed datetime NOT NULL default '0000-00-00 00:00:00',
+    data text NOT NULL,
+    seen smallint NOT NULL DEFAULT '0',
+    deleted smallint NOT NULL DEFAULT '0',
+    answered smallint NOT NULL DEFAULT '0',
+    forwarded smallint NOT NULL DEFAULT '0',
+    flagged smallint NOT NULL DEFAULT '0',
+    mdnsent smallint NOT NULL DEFAULT '0',
+    PRIMARY KEY (user_id, mailbox, uid)
+);
+
+CREATE INDEX ix_cache_messages_changed ON cache_messages (changed);
diff --git a/SQL/sqlite.update.sql b/SQL/sqlite.update.sql
index 41ab020..378072c 100644
--- a/SQL/sqlite.update.sql
+++ b/SQL/sqlite.update.sql
@@ -223,10 +223,10 @@
 CREATE INDEX ix_contacts_user_id ON contacts(user_id, email);
 DROP TABLE contacts_tmp;
 
+
 DELETE FROM messages;
 DELETE FROM cache;
 CREATE INDEX ix_contactgroupmembers_contact_id ON contactgroupmembers (contact_id);
-
 
 -- Updates from version 0.6-stable
 
@@ -247,3 +247,42 @@
 );
 
 CREATE UNIQUE INDEX ix_searches_user_type_name (user_id, type, name);
+
+DROP TABLE messages;
+
+CREATE TABLE cache_index (
+    user_id integer NOT NULL,
+    mailbox varchar(255) NOT NULL,
+    changed datetime NOT NULL default '0000-00-00 00:00:00',
+    data text NOT NULL,
+    PRIMARY KEY (user_id, mailbox)
+);
+
+CREATE INDEX ix_cache_index_changed ON cache_index (changed);
+
+CREATE TABLE cache_thread (
+    user_id integer NOT NULL,
+    mailbox varchar(255) NOT NULL,
+    changed datetime NOT NULL default '0000-00-00 00:00:00',
+    data text NOT NULL,
+    PRIMARY KEY (user_id, mailbox)
+);
+
+CREATE INDEX ix_cache_thread_changed ON cache_thread (changed);
+
+CREATE TABLE cache_messages (
+    user_id integer NOT NULL,
+    mailbox varchar(255) NOT NULL,
+    uid integer NOT NULL,
+    changed datetime NOT NULL default '0000-00-00 00:00:00',
+    data text NOT NULL,
+    seen smallint NOT NULL DEFAULT '0',
+    deleted smallint NOT NULL DEFAULT '0',
+    answered smallint NOT NULL DEFAULT '0',
+    forwarded smallint NOT NULL DEFAULT '0',
+    flagged smallint NOT NULL DEFAULT '0',
+    mdnsent smallint NOT NULL DEFAULT '0',
+    PRIMARY KEY (user_id, mailbox, uid)
+);
+
+CREATE INDEX ix_cache_messages_changed ON cache_messages (changed);
diff --git a/program/include/main.inc b/program/include/main.inc
index 4c24ce3..3513a07c 100644
--- a/program/include/main.inc
+++ b/program/include/main.inc
@@ -169,11 +169,17 @@
   // get target timestamp
   $ts = get_offset_time($rcmail->config->get('message_cache_lifetime', '30d'), -1);
 
-  $db->query("DELETE FROM ".get_table_name('messages')."
-             WHERE  created < " . $db->fromunixtime($ts));
+  $db->query("DELETE FROM ".get_table_name('cache_messages')
+        ." WHERE changed < " . $db->fromunixtime($ts));
 
-  $db->query("DELETE FROM ".get_table_name('cache')."
-              WHERE  created < " . $db->fromunixtime($ts));
+  $db->query("DELETE FROM ".get_table_name('cache_index')
+        ." WHERE changed < " . $db->fromunixtime($ts));
+
+  $db->query("DELETE FROM ".get_table_name('cache_thread')
+        ." WHERE changed < " . $db->fromunixtime($ts));
+
+  $db->query("DELETE FROM ".get_table_name('cache')
+        ." WHERE created < " . $db->fromunixtime($ts));
 }
 
 
diff --git a/program/include/rcube_imap.php b/program/include/rcube_imap.php
index 97b080a..a15a592 100644
--- a/program/include/rcube_imap.php
+++ b/program/include/rcube_imap.php
@@ -48,11 +48,11 @@
     public $conn;
 
     /**
-     * Instance of rcube_mdb2
+     * Instance of rcube_imap_cache
      *
-     * @var rcube_mdb2
+     * @var rcube_imap_cache
      */
-    private $db;
+    private $mcache;
 
     /**
      * Instance of rcube_cache
@@ -60,6 +60,14 @@
      * @var rcube_cache
      */
     private $cache;
+
+    /**
+     * Internal (in-memory) cache
+     *
+     * @var array
+     */
+    private $icache = array();
+
     private $mailbox = 'INBOX';
     private $delimiter = NULL;
     private $namespace = NULL;
@@ -68,8 +76,6 @@
     private $default_charset = 'ISO-8859-1';
     private $struct_charset = NULL;
     private $default_folders = array('INBOX');
-    private $messages_caching = false;
-    private $icache = array();
     private $uid_id_map = array();
     private $msg_headers = array();
     public  $search_set = NULL;
@@ -78,10 +84,10 @@
     private $search_sort_field = '';
     private $search_threads = false;
     private $search_sorted = false;
-    private $db_header_fields = array('idx', 'uid', 'subject', 'from', 'to', 'cc', 'date', 'size');
     private $options = array('auth_method' => 'check');
     private $host, $user, $pass, $port, $ssl;
     private $caching = false;
+    private $messages_caching = false;
 
     /**
      * All (additional) headers used (in any way) by Roundcube
@@ -214,6 +220,8 @@
     function close()
     {
         $this->conn->closeConnection();
+        if ($this->mcache)
+            $this->mcache->close();
     }
 
 
@@ -689,7 +697,7 @@
 
             if ($status) {
                 $this->set_folder_stats($mailbox, 'cnt', $res['msgcount']);
-                $this->set_folder_stats($mailbox, 'maxuid', $res['maxuid'] ? $this->_id2uid($res['maxuid'], $mailbox) : 0);
+                $this->set_folder_stats($mailbox, 'maxuid', $res['maxuid'] ? $this->id2uid($res['maxuid'], $mailbox) : 0);
             }
         }
         // RECENT count is fetched a bit different
@@ -722,9 +730,9 @@
             $count = is_array($index) ? $index['COUNT'] : 0;
 
             if ($mode == 'ALL') {
-                if ($need_uid && $this->messages_caching) {
-                    // Save messages index for check_cache_status()
-                    $this->icache['all_undeleted_idx'] = $index['ALL'];
+                if ($this->messages_caching) {
+                    // Save additional info required by cache status check
+                    $this->icache['undeleted_idx'] = array($mailbox, $index['ALL'], $index['COUNT']);
                 }
                 if ($status) {
                     $this->set_folder_stats($mailbox, 'cnt', $count);
@@ -739,7 +747,7 @@
                 $count = $this->conn->countMessages($mailbox);
                 if ($status) {
                     $this->set_folder_stats($mailbox,'cnt', $count);
-                    $this->set_folder_stats($mailbox, 'maxuid', $count ? $this->_id2uid($count, $mailbox) : 0);
+                    $this->set_folder_stats($mailbox, 'maxuid', $count ? $this->id2uid($count, $mailbox) : 0);
                 }
             }
         }
@@ -774,7 +782,7 @@
                 'maxuid'   => $dcount ? max(array_keys($this->icache['threads']['depth'])) : 0,
             );
         }
-        else if (is_array($result = $this->_fetch_threads($mailbox))) {
+        else if (is_array($result = $this->fetch_threads($mailbox))) {
             $dcount = count($result[1]);
             $result = array(
                 'count'    => count($result[0]),
@@ -817,11 +825,11 @@
      * @param   string   $sort_field Header field to sort by
      * @param   string   $sort_order Sort order [ASC|DESC]
      * @param   int      $slice      Number of slice items to extract from result array
+     *
      * @return  array    Indexed array with message header objects
-     * @access  private
      * @see     rcube_imap::list_headers
      */
-    private function _list_headers($mailbox='', $page=NULL, $sort_field=NULL, $sort_order=NULL, $recursive=false, $slice=0)
+    private function _list_headers($mailbox='', $page=NULL, $sort_field=NULL, $sort_order=NULL, $slice=0)
     {
         if (!strlen($mailbox))
             return array();
@@ -831,41 +839,39 @@
             return $this->_list_header_set($mailbox, $page, $sort_field, $sort_order, $slice);
 
         if ($this->threading)
-            return $this->_list_thread_headers($mailbox, $page, $sort_field, $sort_order, $recursive, $slice);
+            return $this->_list_thread_headers($mailbox, $page, $sort_field, $sort_order, $slice);
 
         $this->_set_sort_order($sort_field, $sort_order);
 
-        $page         = $page ? $page : $this->list_page;
-        $cache_key    = $mailbox.'.msg';
+        $page = $page ? $page : $this->list_page;
 
-        if ($this->messages_caching) {
-            // cache is OK, we can get messages from local cache
-            // (assume cache is in sync when in recursive mode)
-            if ($recursive || $this->check_cache_status($mailbox, $cache_key)>0) {
-                $start_msg = ($page-1) * $this->page_size;
-                $a_msg_headers = $this->get_message_cache($cache_key, $start_msg,
-                    $start_msg+$this->page_size, $this->sort_field, $this->sort_order);
-                $result = array_values($a_msg_headers);
-                if ($slice)
-                    $result = array_slice($result, -$slice, $slice);
-                return $result;
-            }
-            // cache is incomplete, sync it (all messages in the folder)
-            else if (!$recursive) {
-                $this->sync_header_index($mailbox);
-                return $this->_list_headers($mailbox, $page, $this->sort_field, $this->sort_order, true, $slice);
-            }
+        // Use messages cache
+        if ($mcache = $this->get_mcache_engine()) {
+            $msg_index = $mcache->get_index($mailbox, $this->sort_field, $this->sort_order);
+
+            if (empty($msg_index))
+                return array();
+
+            $from      = ($page-1) * $this->page_size;
+            $to        = $from + $this->page_size;
+            $msg_index = array_values($msg_index); // UIDs
+            $is_uid    = true;
+            $sorted    = true;
+
+            if ($from || $to)
+                $msg_index = array_slice($msg_index, $from, $to - $from);
+
+            if ($slice)
+                $msg_index = array_slice($msg_index, -$slice, $slice);
+
+            $a_msg_headers = $mcache->get_messages($mailbox, $msg_index);
         }
-
         // retrieve headers from IMAP
-        $a_msg_headers = array();
-
         // use message index sort as default sorting (for better performance)
-        if (!$this->sort_field) {
+        else if (!$this->sort_field) {
             if ($this->skip_deleted) {
                 // @TODO: this could be cached
                 if ($msg_index = $this->_search_index($mailbox, 'ALL UNDELETED')) {
-                    $max = max($msg_index);
                     list($begin, $end) = $this->_get_message_range(count($msg_index), $page);
                     $msg_index = array_slice($msg_index, $begin, $end-$begin);
                 }
@@ -882,46 +888,42 @@
 
             // fetch reqested headers from server
             if ($msg_index)
-                $this->_fetch_headers($mailbox, join(",", $msg_index), $a_msg_headers, $cache_key);
+                $a_msg_headers = $this->fetch_headers($mailbox, $msg_index);
         }
         // use SORT command
         else if ($this->get_capability('SORT') &&
             // Courier-IMAP provides SORT capability but allows to disable it by admin (#1486959)
-            ($msg_index = $this->conn->sort($mailbox, $this->sort_field, $this->skip_deleted ? 'UNDELETED' : '')) !== false
+            ($msg_index = $this->conn->sort($mailbox, $this->sort_field,
+                $this->skip_deleted ? 'UNDELETED' : '', true)) !== false
         ) {
             if (!empty($msg_index)) {
                 list($begin, $end) = $this->_get_message_range(count($msg_index), $page);
-                $max = max($msg_index);
                 $msg_index = array_slice($msg_index, $begin, $end-$begin);
+                $is_uid    = true;
 
                 if ($slice)
                     $msg_index = array_slice($msg_index, ($this->sort_order == 'DESC' ? 0 : -$slice), $slice);
 
                 // fetch reqested headers from server
-                $this->_fetch_headers($mailbox, join(',', $msg_index), $a_msg_headers, $cache_key);
+                $a_msg_headers = $this->fetch_headers($mailbox, $msg_index, true);
             }
         }
         // fetch specified header for all messages and sort
-        else if ($a_index = $this->conn->fetchHeaderIndex($mailbox, "1:*", $this->sort_field, $this->skip_deleted)) {
-            asort($a_index); // ASC
-            $msg_index = array_keys($a_index);
-            $max = max($msg_index);
+        else if ($msg_index = $this->conn->fetchHeaderIndex($mailbox, "1:*",
+            $this->sort_field, $this->skip_deleted, true)
+        ) {
+            asort($msg_index); // ASC
+            $msg_index = array_keys($msg_index);
             list($begin, $end) = $this->_get_message_range(count($msg_index), $page);
             $msg_index = array_slice($msg_index, $begin, $end-$begin);
+            $is_uid    = true;
 
             if ($slice)
                 $msg_index = array_slice($msg_index, ($this->sort_order == 'DESC' ? 0 : -$slice), $slice);
 
             // fetch reqested headers from server
-            $this->_fetch_headers($mailbox, join(",", $msg_index), $a_msg_headers, $cache_key);
+            $a_msg_headers = $this->fetch_headers($mailbox, $msg_index, true);
         }
-
-        // delete cached messages with a higher index than $max+1
-        // Changed $max to $max+1 to fix this bug : #1484295
-        $this->clear_message_cache($cache_key, $max + 1);
-
-        // kick child process to sync cache
-        // ...
 
         // return empty array if no messages found
         if (!is_array($a_msg_headers) || empty($a_msg_headers))
@@ -929,10 +931,10 @@
 
         // use this class for message sorting
         $sorter = new rcube_header_sorter();
-        $sorter->set_sequence_numbers($msg_index);
+        $sorter->set_index($msg_index, $is_uid);
         $sorter->sort_headers($a_msg_headers);
 
-        if ($this->sort_order == 'DESC')
+        if ($this->sort_order == 'DESC' && !$sorted)
             $a_msg_headers = array_reverse($a_msg_headers);
 
         return array_values($a_msg_headers);
@@ -946,27 +948,28 @@
      * @param   int      $page       Current page to list
      * @param   string   $sort_field Header field to sort by
      * @param   string   $sort_order Sort order [ASC|DESC]
-     * @param   boolean  $recursive  True if called recursively
      * @param   int      $slice      Number of slice items to extract from result array
+     *
      * @return  array    Indexed array with message header objects
-     * @access  private
      * @see     rcube_imap::list_headers
      */
-    private function _list_thread_headers($mailbox, $page=NULL, $sort_field=NULL, $sort_order=NULL, $recursive=false, $slice=0)
+    private function _list_thread_headers($mailbox, $page=NULL, $sort_field=NULL, $sort_order=NULL, $slice=0)
     {
         $this->_set_sort_order($sort_field, $sort_order);
 
-        $page = $page ? $page : $this->list_page;
-//    $cache_key = $mailbox.'.msg';
-//    $cache_status = $this->check_cache_status($mailbox, $cache_key);
+        $page   = $page ? $page : $this->list_page;
+        $mcache = $this->get_mcache_engine();
 
-        // get all threads (default sort order)
-        list ($thread_tree, $msg_depth, $has_children) = $this->_fetch_threads($mailbox);
+        // get all threads (not sorted)
+        if ($mcache)
+            list ($thread_tree, $msg_depth, $has_children) = $mcache->get_thread($mailbox);
+        else
+            list ($thread_tree, $msg_depth, $has_children) = $this->fetch_threads($mailbox);
 
         if (empty($thread_tree))
             return array();
 
-        $msg_index = $this->_sort_threads($mailbox, $thread_tree);
+        $msg_index = $this->sort_threads($mailbox, $thread_tree);
 
         return $this->_fetch_thread_headers($mailbox,
             $thread_tree, $msg_depth, $has_children, $msg_index, $page, $slice);
@@ -974,14 +977,20 @@
 
 
     /**
-     * Private method for fetching threads data
+     * Method for fetching threads data
      *
-     * @param   string   $mailbox Mailbox/folder name
+     * @param  string $mailbox  Folder name
+     * @param  bool   $force    Use IMAP server, no cache
+     *
      * @return  array    Array with thread data
-     * @access  private
      */
-    private function _fetch_threads($mailbox)
+    function fetch_threads($mailbox, $force = false)
     {
+        if (!$force && ($mcache = $this->get_mcache_engine())) {
+            // don't store in self's internal cache, cache has it's own internal cache
+            return $mcache->get_thread($mailbox);
+        }
+
         if (empty($this->icache['threads'])) {
             // get all threads
             $result = $this->conn->thread($mailbox, $this->threading,
@@ -1012,12 +1021,12 @@
      * @param array   $msg_index    Messages index
      * @param int     $page         List page number
      * @param int     $slice        Number of threads to slice
+     *
      * @return array  Messages headers
      * @access  private
      */
     private function _fetch_thread_headers($mailbox, $thread_tree, $msg_depth, $has_children, $msg_index, $page, $slice=0)
     {
-        $cache_key = $mailbox.'.msg';
         // now get IDs for current page
         list($begin, $end) = $this->_get_message_range(count($msg_index), $page);
         $msg_index = array_slice($msg_index, $begin, $end-$begin);
@@ -1038,7 +1047,7 @@
         }
 
         // fetch reqested headers from server
-        $this->_fetch_headers($mailbox, $all_ids, $a_msg_headers, $cache_key);
+        $a_msg_headers = $this->fetch_headers($mailbox, $all_ids);
 
         // return empty array if no messages found
         if (!is_array($a_msg_headers) || empty($a_msg_headers))
@@ -1046,7 +1055,7 @@
 
         // use this class for message sorting
         $sorter = new rcube_header_sorter();
-        $sorter->set_sequence_numbers($all_ids);
+        $sorter->set_index($all_ids);
         $sorter->sort_headers($a_msg_headers);
 
         // Set depth, has_children and unread_children fields in headers
@@ -1135,11 +1144,11 @@
                 $msgs = array_slice($msgs, -$slice, $slice);
 
             // fetch headers
-            $this->_fetch_headers($mailbox, join(',',$msgs), $a_msg_headers, NULL);
+            $a_msg_headers = $this->fetch_headers($mailbox, $msgs);
 
             // I didn't found in RFC that FETCH always returns messages sorted by index
             $sorter = new rcube_header_sorter();
-            $sorter->set_sequence_numbers($msgs);
+            $sorter->set_index($msgs);
             $sorter->sort_headers($a_msg_headers);
 
             return array_values($a_msg_headers);
@@ -1165,10 +1174,10 @@
                 $msgs = array_slice($msgs, -$slice, $slice);
 
             // fetch headers
-            $this->_fetch_headers($mailbox, join(',',$msgs), $a_msg_headers, NULL);
+            $a_msg_headers = $this->fetch_headers($mailbox, $msgs);
 
             $sorter = new rcube_header_sorter();
-            $sorter->set_sequence_numbers($msgs);
+            $sorter->set_index($msgs);
             $sorter->sort_headers($a_msg_headers);
 
             return array_values($a_msg_headers);
@@ -1184,21 +1193,22 @@
                 if ($slice)
                     $msgs = array_slice($msgs, -$slice, $slice);
                 // ...and fetch headers
-                $this->_fetch_headers($mailbox, join(',', $msgs), $a_msg_headers, NULL);
+                $a_msg_headers = $this->fetch_headers($mailbox, $msgs);
+
 
                 // return empty array if no messages found
                 if (!is_array($a_msg_headers) || empty($a_msg_headers))
                     return array();
 
                 $sorter = new rcube_header_sorter();
-                $sorter->set_sequence_numbers($msgs);
+                $sorter->set_index($msgs);
                 $sorter->sort_headers($a_msg_headers);
 
                 return array_values($a_msg_headers);
             }
             else {
                 // for small result set we can fetch all messages headers
-                $this->_fetch_headers($mailbox, join(',', $msgs), $a_msg_headers, NULL);
+                $a_msg_headers = $this->fetch_headers($mailbox, $msgs);
 
                 // return empty array if no messages found
                 if (!is_array($a_msg_headers) || empty($a_msg_headers))
@@ -1256,7 +1266,7 @@
 
         $this->_set_sort_order($sort_field, $sort_order);
 
-        $msg_index = $this->_sort_threads($mailbox, $thread_tree, array_keys($msg_depth));
+        $msg_index = $this->sort_threads($mailbox, $thread_tree, array_keys($msg_depth));
 
         return $this->_fetch_thread_headers($mailbox,
             $thread_tree, $msg_depth, $has_children, $msg_index, $page, $slice=0);
@@ -1297,64 +1307,37 @@
 
 
     /**
-     * Fetches message headers (used for loop)
+     * Fetches messages headers
      *
-     * @param  string  $mailbox       Mailbox name
-     * @param  string  $msgs          Message index to fetch
-     * @param  array   $a_msg_headers Reference to message headers array
-     * @param  string  $cache_key     Cache index key
-     * @return int     Messages count
+     * @param  string  $mailbox  Mailbox name
+     * @param  array   $msgs     Messages sequence numbers
+     * @param  bool    $is_uid   Enable if $msgs numbers are UIDs
+     * @param  bool    $force    Disables cache use
+     *
+     * @return array Messages headers indexed by UID
      * @access private
      */
-    private function _fetch_headers($mailbox, $msgs, &$a_msg_headers, $cache_key)
+    function fetch_headers($mailbox, $msgs, $is_uid = false, $force = false)
     {
+        if (empty($msgs))
+            return array();
+
+        if (!$force && ($mcache = $this->get_mcache_engine())) {
+            return $mcache->get_messages($mailbox, $msgs, $is_uid);
+        }
+
         // fetch reqested headers from server
-        $a_header_index = $this->conn->fetchHeaders(
-            $mailbox, $msgs, false, false, $this->get_fetch_headers());
+        $index = $this->conn->fetchHeaders(
+            $mailbox, $msgs, $is_uid, false, $this->get_fetch_headers());
 
-        if (empty($a_header_index))
-            return 0;
+        if (empty($index))
+            return array();
 
-        foreach ($a_header_index as $i => $headers) {
+        foreach ($index as $headers) {
             $a_msg_headers[$headers->uid] = $headers;
         }
 
-        // Update cache
-        if ($this->messages_caching && $cache_key) {
-            // cache is incomplete?
-            $cache_index = $this->get_message_cache_index($cache_key);
-
-            foreach ($a_header_index as $headers) {
-                // message in cache
-                if ($cache_index[$headers->id] == $headers->uid) {
-                    unset($cache_index[$headers->id]);
-                    continue;
-                }
-                // wrong UID at this position
-                if ($cache_index[$headers->id]) {
-                    $for_remove[] = $cache_index[$headers->id];
-                    unset($cache_index[$headers->id]);
-                }
-                // message UID in cache but at wrong position
-                if (is_int($key = array_search($headers->uid, $cache_index))) {
-                    $for_remove[] = $cache_index[$key];
-                    unset($cache_index[$key]);
-                }
-
-                $for_create[] = $headers->uid;
-            }
-
-            if ($for_remove)
-                $this->remove_message_cache($cache_key, $for_remove);
-
-            // add messages to cache
-            foreach ((array)$for_create as $uid) {
-                $headers = $a_msg_headers[$uid];
-                $this->add_message_cache($cache_key, $headers->id, $headers, NULL, true);
-            }
-        }
-
-        return count($a_msg_headers);
+        return $a_msg_headers;
     }
 
 
@@ -1471,7 +1454,7 @@
             }
             else {
                 $a_index = $this->conn->fetchHeaderIndex($mailbox,
-	                join(',', $this->search_set), $this->sort_field, $this->skip_deleted);
+                    join(',', $this->search_set), $this->sort_field, $this->skip_deleted);
 
                 if (is_array($a_index)) {
                     if ($this->sort_order=="ASC")
@@ -1492,50 +1475,62 @@
             return $this->icache[$key];
 
         // check local cache
-        $cache_key = $mailbox.'.msg';
-        $cache_status = $this->check_cache_status($mailbox, $cache_key);
-
-        // cache is OK
-        if ($cache_status>0) {
-            $a_index = $this->get_message_cache_index($cache_key,
-                $this->sort_field, $this->sort_order);
-            return array_keys($a_index);
+        if ($mcache = $this->get_mcache_engine()) {
+            $a_index = $mcache->get_index($mailbox, $this->sort_field, $this->sort_order);
+            $this->icache[$key] = array_keys($a_index);
+        }
+        // fetch from IMAP server
+        else {
+            $this->icache[$key] = $this->message_index_direct(
+                $mailbox, $this->sort_field, $this->sort_order);
         }
 
+        return $this->icache[$key];
+    }
+
+
+    /**
+     * Return sorted array of message IDs (not UIDs) directly from IMAP server.
+     * Doesn't use cache and ignores current search settings.
+     *
+     * @param string $mailbox    Mailbox to get index from
+     * @param string $sort_field Sort column
+     * @param string $sort_order Sort order [ASC, DESC]
+     *
+     * @return array Indexed array with message IDs
+     */
+    function message_index_direct($mailbox, $sort_field = null, $sort_order = null)
+    {
         // use message index sort as default sorting
-        if (!$this->sort_field) {
+        if (!$sort_field) {
             if ($this->skip_deleted) {
                 $a_index = $this->_search_index($mailbox, 'ALL');
             } else if ($max = $this->_messagecount($mailbox)) {
                 $a_index = range(1, $max);
             }
 
-            if ($a_index !== false && $this->sort_order == 'DESC')
+            if ($a_index !== false && $sort_order == 'DESC')
                 $a_index = array_reverse($a_index);
-
-            $this->icache[$key] = $a_index;
         }
         // fetch complete message index
         else if ($this->get_capability('SORT') &&
             ($a_index = $this->conn->sort($mailbox,
-                $this->sort_field, $this->skip_deleted ? 'UNDELETED' : '')) !== false
+                $sort_field, $this->skip_deleted ? 'UNDELETED' : '')) !== false
         ) {
-            if ($this->sort_order == 'DESC')
+            if ($sort_order == 'DESC')
                 $a_index = array_reverse($a_index);
-
-            $this->icache[$key] = $a_index;
         }
         else if ($a_index = $this->conn->fetchHeaderIndex(
-            $mailbox, "1:*", $this->sort_field, $this->skip_deleted)) {
-            if ($this->sort_order=="ASC")
+            $mailbox, "1:*", $sort_field, $skip_deleted)) {
+            if ($sort_order=="ASC")
                 asort($a_index);
-            else if ($this->sort_order=="DESC")
+            else if ($sort_order=="DESC")
                 arsort($a_index);
 
-            $this->icache[$key] = array_keys($a_index);
+            $a_index = array_keys($a_index);
         }
 
-        return $this->icache[$key] !== false ? $this->icache[$key] : array();
+        return $a_index !== false ? $a_index : array();
     }
 
 
@@ -1567,19 +1562,9 @@
         // have stored it in RAM
         if (isset($this->icache[$key]))
             return $this->icache[$key];
-/*
-        // check local cache
-        $cache_key = $mailbox.'.msg';
-        $cache_status = $this->check_cache_status($mailbox, $cache_key);
 
-        // cache is OK
-        if ($cache_status>0) {
-            $a_index = $this->get_message_cache_index($cache_key, $this->sort_field, $this->sort_order);
-            return array_keys($a_index);
-        }
-*/
         // get all threads (default sort order)
-        list ($thread_tree) = $this->_fetch_threads($mailbox);
+        list ($thread_tree) = $this->fetch_threads($mailbox);
 
         $this->icache[$key] = $this->_flatten_threads($mailbox, $thread_tree);
 
@@ -1591,7 +1576,7 @@
      * Return array of threaded messages (all, not only roots)
      *
      * @param string $mailbox     Mailbox to get index from
-     * @param array  $thread_tree Threaded messages array (see _fetch_threads())
+     * @param array  $thread_tree Threaded messages array (see fetch_threads())
      * @param array  $ids         Message IDs if we know what we need (e.g. search result)
      *                            for better performance
      * @return array Indexed array with message IDs
@@ -1603,7 +1588,7 @@
         if (empty($thread_tree))
             return array();
 
-        $msg_index = $this->_sort_threads($mailbox, $thread_tree, $ids);
+        $msg_index = $this->sort_threads($mailbox, $thread_tree, $ids);
 
         if ($this->sort_order == 'DESC')
             $msg_index = array_reverse($msg_index);
@@ -1619,99 +1604,6 @@
         }
 
         return $all_ids;
-    }
-
-
-    /**
-     * @param string $mailbox Mailbox name
-     * @access private
-     */
-    private function sync_header_index($mailbox)
-    {
-        $cache_key = $mailbox.'.msg';
-        $cache_index = $this->get_message_cache_index($cache_key);
-        $chunk_size = 1000;
-
-        // cache is empty, get all messages
-        if (is_array($cache_index) && empty($cache_index)) {
-            $max = $this->_messagecount($mailbox);
-            // syncing a big folder maybe slow
-            @set_time_limit(0);
-            $start = 1;
-            $end   = min($chunk_size, $max);
-            while (true) {
-                // do this in loop to save memory (1000 msgs ~= 10 MB)
-                if ($headers = $this->conn->fetchHeaders($mailbox,
-                    "$start:$end", false, false, $this->get_fetch_headers())
-                ) {
-                    foreach ($headers as $header) {
-                        $this->add_message_cache($cache_key, $header->id, $header, NULL, true);
-                    }
-                }
-                if ($end - $start < $chunk_size - 1)
-                    break;
-
-                $end   = min($end+$chunk_size, $max);
-                $start += $chunk_size;
-            }
-            return;
-        }
-
-        // fetch complete message index
-        if (isset($this->icache['folder_index']))
-            $a_message_index = &$this->icache['folder_index'];
-        else
-            $a_message_index = $this->conn->fetchHeaderIndex($mailbox, "1:*", 'UID', $this->skip_deleted);
-
-        if ($a_message_index === false || $cache_index === null)
-            return;
-
-        // compare cache index with real index
-        foreach ($a_message_index as $id => $uid) {
-            // message in cache at correct position
-            if ($cache_index[$id] == $uid) {
-                unset($cache_index[$id]);
-                continue;
-            }
-
-            // other message at this position
-            if (isset($cache_index[$id])) {
-                $for_remove[] = $cache_index[$id];
-                unset($cache_index[$id]);
-            }
-
-            // message in cache but at wrong position
-            if (is_int($key = array_search($uid, $cache_index))) {
-                $for_remove[] = $uid;
-                unset($cache_index[$key]);
-            }
-
-            $for_update[] = $id;
-        }
-
-        // remove messages at wrong positions and those deleted that are still in cache_index
-        if (!empty($for_remove))
-            $cache_index = array_merge($cache_index, $for_remove);
-
-        if (!empty($cache_index))
-            $this->remove_message_cache($cache_key, $cache_index);
-
-        // fetch complete headers and add to cache
-        if (!empty($for_update)) {
-            // syncing a big folder maybe slow
-            @set_time_limit(0);
-            // To save memory do this in chunks
-            $for_update = array_chunk($for_update, $chunk_size);
-            foreach ($for_update as $uids) {
-                if ($headers = $this->conn->fetchHeaders($mailbox,
-                    $uids, false, false, $this->get_fetch_headers())
-                ) {
-                    foreach ($headers as $header) {
-                        $this->add_message_cache($cache_key, $header->id, $header, NULL, true);
-                    }
-                }
-            }
-        }
     }
 
 
@@ -1750,8 +1642,8 @@
      * @param string $criteria   Search criteria
      * @param string $charset    Charset
      * @param string $sort_field Sorting field
+     *
      * @return array   search results as list of message ids
-     * @access private
      * @see rcube_imap::search()
      */
     private function _search_index($mailbox, $criteria='ALL', $charset=NULL, $sort_field=NULL)
@@ -1773,9 +1665,9 @@
             if ($a_messages !== false) {
                 list ($thread_tree, $msg_depth, $has_children) = $a_messages;
                 $a_messages = array(
-                    'tree' 	=> $thread_tree,
-	                'depth'	=> $msg_depth,
-	                'children' => $has_children
+                    'tree' => $thread_tree,
+                    'depth'=> $msg_depth,
+                    'children' => $has_children
                 );
             }
 
@@ -1787,7 +1679,7 @@
             $a_messages = $this->conn->sort($mailbox, $sort_field, $criteria, false, $charset);
 
             // Error, try with US-ASCII (RFC5256: SORT/THREAD must support US-ASCII and UTF-8,
-            // but I've seen that Courier doesn't support UTF-8)
+            // but I've seen Courier with disabled UTF-8 support)
             if ($a_messages === false && $charset && $charset != 'US-ASCII')
                 $a_messages = $this->conn->sort($mailbox, $sort_field,
                     $this->convert_criteria($criteria, $charset), false, 'US-ASCII');
@@ -1829,8 +1721,8 @@
      * @param  string  $mailbox Mailbox name to search in
      * @param  string  $str     Search string
      * @param  boolean $ret_uid True if UIDs should be returned
+     *
      * @return array   Search results as list of message IDs or UIDs
-     * @access public
      */
     function search_once($mailbox='', $str=NULL, $ret_uid=false)
     {
@@ -1884,43 +1776,53 @@
      * @param string $mailbox     Mailbox name
      * @param  array $thread_tree Unsorted thread tree (rcube_imap_generic::thread() result)
      * @param  array $ids         Message IDs if we know what we need (e.g. search result)
+     *
      * @return array Sorted roots IDs
-     * @access private
      */
-    private function _sort_threads($mailbox, $thread_tree, $ids=NULL)
+    function sort_threads($mailbox, $thread_tree, $ids = null)
     {
-        // THREAD=ORDEREDSUBJECT: 	sorting by sent date of root message
-        // THREAD=REFERENCES: 	sorting by sent date of root message
-        // THREAD=REFS: 		sorting by the most recent date in each thread
+        // THREAD=ORDEREDSUBJECT: sorting by sent date of root message
+        // THREAD=REFERENCES:     sorting by sent date of root message
+        // THREAD=REFS:           sorting by the most recent date in each thread
+
         // default sorting
         if (!$this->sort_field || ($this->sort_field == 'date' && $this->threading == 'REFS')) {
             return array_keys((array)$thread_tree);
-          }
-        // here we'll implement REFS sorting, for performance reason
-        else { // ($sort_field == 'date' && $this->threading != 'REFS')
+        }
+        // here we'll implement REFS sorting
+        else {
+            if ($mcache = $this->get_mcache_engine()) {
+                $a_index = $mcache->get_index($mailbox, $this->sort_field, 'ASC');
+                if (is_array($a_index)) {
+                    $a_index = array_keys($a_index);
+                    // now we must remove IDs that doesn't exist in $ids
+                    if (!empty($ids))
+                        $a_index = array_intersect($a_index, $ids);
+                }
+            }
             // use SORT command
-            if ($this->get_capability('SORT') && 
+            else if ($this->get_capability('SORT') &&
                 ($a_index = $this->conn->sort($mailbox, $this->sort_field,
-	                !empty($ids) ? $ids : ($this->skip_deleted ? 'UNDELETED' : ''))) !== false
+                    !empty($ids) ? $ids : ($this->skip_deleted ? 'UNDELETED' : ''))) !== false
             ) {
-	            // return unsorted tree if we've got no index data
-	            if (!$a_index)
-	                return array_keys((array)$thread_tree);
+                // do nothing
             }
             else {
                 // fetch specified headers for all messages and sort them
                 $a_index = $this->conn->fetchHeaderIndex($mailbox, !empty($ids) ? $ids : "1:*",
-	                $this->sort_field, $this->skip_deleted);
+                    $this->sort_field, $this->skip_deleted);
 
-	            // return unsorted tree if we've got no index data
-	            if (!$a_index)
-	                return array_keys((array)$thread_tree);
-
-                asort($a_index); // ASC
-	            $a_index = array_values($a_index);
+                // return unsorted tree if we've got no index data
+                if (!empty($a_index)) {
+                    asort($a_index); // ASC
+                    $a_index = array_values($a_index);
+                }
             }
 
-	        return $this->_sort_thread_refs($thread_tree, $a_index);
+            if (empty($a_index))
+                return array_keys((array)$thread_tree);
+
+            return $this->_sort_thread_refs($thread_tree, $a_index);
         }
     }
 
@@ -1928,10 +1830,10 @@
     /**
      * THREAD=REFS sorting implementation
      *
-     * @param  array $tree  Thread tree array (message identifiers as keys)
-     * @param  array $index Array of sorted message identifiers
+     * @param  array $tree   Thread tree array (message identifiers as keys)
+     * @param  array $index  Array of sorted message identifiers
+     *
      * @return array   Array of sorted roots messages
-     * @access private
      */
     private function _sort_thread_refs($tree, $index)
     {
@@ -1980,7 +1882,7 @@
     {
         if (!empty($this->search_string))
             $this->search_set = $this->search('', $this->search_string, $this->search_charset,
-    	        $this->search_sort_field, $this->search_threads, $this->search_sorted);
+                $this->search_sort_field, $this->search_threads, $this->search_sorted);
 
         return $this->get_search_set();
     }
@@ -2008,32 +1910,25 @@
     /**
      * Return message headers object of a specific message
      *
-     * @param int     $id       Message ID
+     * @param int     $id       Message sequence ID or UID
      * @param string  $mailbox  Mailbox to read from
-     * @param boolean $is_uid   True if $id is the message UID
-     * @param boolean $bodystr  True if we need also BODYSTRUCTURE in headers
-     * @return object Message headers representation
+     * @param bool    $force    True to skip cache
+     *
+     * @return rcube_mail_header Message headers
      */
-    function get_headers($id, $mailbox=null, $is_uid=true, $bodystr=false)
+    function get_headers($uid, $mailbox = null, $force = false)
     {
         if (!strlen($mailbox)) {
             $mailbox = $this->mailbox;
         }
-        $uid = $is_uid ? $id : $this->_id2uid($id, $mailbox);
 
         // get cached headers
-        if ($uid && ($headers = &$this->get_cached_message($mailbox.'.msg', $uid)))
-            return $headers;
-
-        $headers = $this->conn->fetchHeader(
-            $mailbox, $id, $is_uid, $bodystr, $this->get_fetch_headers());
-
-        // write headers cache
-        if ($headers) {
-            if ($headers->uid && $headers->id)
-                $this->uid_id_map[$mailbox][$headers->uid] = $headers->id;
-
-            $this->add_message_cache($mailbox.'.msg', $headers->id, $headers, NULL, false, true);
+        if (!$force && $uid && ($mcache = $this->get_mcache_engine())) {
+            $headers = $mcache->get_message($mailbox, $uid);
+        }
+        else {
+            $headers = $this->conn->fetchHeader(
+                $mailbox, $uid, true, true, $this->get_fetch_headers());
         }
 
         return $headers;
@@ -2041,33 +1936,43 @@
 
 
     /**
-     * Fetch body structure from the IMAP server and build
+     * Fetch message headers and body structure from the IMAP server and build
      * an object structure similar to the one generated by PEAR::Mail_mimeDecode
      *
-     * @param int    $uid           Message UID to fetch
-     * @param string $structure_str Message BODYSTRUCTURE string (optional)
-     * @return object rcube_message_part Message part tree or False on failure
+     * @param int     $uid      Message UID to fetch
+     * @param string  $mailbox  Mailbox to read from
+     *
+     * @return object rcube_mail_header Message data
      */
-    function &get_structure($uid, $structure_str='')
+    function get_message($uid, $mailbox = null)
     {
-        $cache_key = $this->mailbox.'.msg';
-        $headers = &$this->get_cached_message($cache_key, $uid);
-
-        // return cached message structure
-        if (is_object($headers) && is_object($headers->structure)) {
-            return $headers->structure;
+        if (!strlen($mailbox)) {
+            $mailbox = $this->mailbox;
         }
 
-        if (!$structure_str) {
-            $structure_str = $this->conn->fetchStructureString($this->mailbox, $uid, true);
+        // Check internal cache
+        if (!empty($this->icache['message'])) {
+            if (($headers = $this->icache['message']) && $headers->uid == $uid) {
+                return $headers;
+            }
         }
-        $structure = rcube_mime_struct::parseStructure($structure_str);
-        $struct = false;
 
-        // parse structure and add headers
-        if (!empty($structure)) {
-            $headers = $this->get_headers($uid);
-            $this->_msg_id = $headers->id;
+        $headers = $this->get_headers($uid, $mailbox);
+
+        // structure might be cached
+        if (!empty($headers->structure))
+            return $headers;
+
+        $this->_msg_uid = $uid;
+
+        if (empty($headers->bodystructure)) {
+            $headers->bodystructure = $this->conn->getStructure($mailbox, $uid, true);
+        }
+
+        $structure = $headers->bodystructure;
+
+        if (empty($structure))
+            return $headers;
 
         // set message charset from message headers
         if ($headers->charset)
@@ -2090,7 +1995,7 @@
                 $structure[1] = $m[2];
             }
             else
-                return false;
+                return $headers;
         }
 
         $struct = &$this->_structure_part($structure, 0, '', $headers);
@@ -2103,13 +2008,9 @@
             list($struct->ctype_primary, $struct->ctype_secondary) = explode('/', $struct->mimetype);
         }
 
-        // write structure to cache
-        if ($this->messages_caching)
-            $this->add_message_cache($cache_key, $this->_msg_id, $headers, $struct,
-                $this->icache['message.id'][$uid], true);
-        }
+        $headers->structure = $struct;
 
-        return $struct;
+        return $this->icache['message'] = $headers;
     }
 
 
@@ -2174,7 +2075,7 @@
             // headers for parts on all levels
             if ($mime_part_headers) {
                 $mime_part_headers = $this->conn->fetchMIMEHeaders($this->mailbox,
-                    $this->_msg_id, $mime_part_headers);
+                    $this->_msg_uid, $mime_part_headers);
             }
 
             $struct->parts = array();
@@ -2276,7 +2177,7 @@
         if ($struct->ctype_primary == 'message' || ($struct->ctype_parameters['name'] && !$struct->content_id)) {
             if (empty($mime_headers)) {
                 $mime_headers = $this->conn->fetchPartHeader(
-                    $this->mailbox, $this->_msg_id, false, $struct->mime_id);
+                    $this->mailbox, $this->_msg_uid, true, $struct->mime_id);
             }
 
             if (is_string($mime_headers))
@@ -2339,7 +2240,7 @@
             if ($i<2) {
                 if (!$headers) {
                     $headers = $this->conn->fetchPartHeader(
-                        $this->mailbox, $this->_msg_id, false, $part->mime_id);
+                        $this->mailbox, $this->_msg_uid, true, $part->mime_id);
                 }
                 $filename_mime = '';
                 $i = 0;
@@ -2358,7 +2259,7 @@
             if ($i<2) {
                 if (!$headers) {
                     $headers = $this->conn->fetchPartHeader(
-                            $this->mailbox, $this->_msg_id, false, $part->mime_id);
+                            $this->mailbox, $this->_msg_uid, true, $part->mime_id);
                 }
                 $filename_encoded = '';
                 $i = 0; $matches = array();
@@ -2377,7 +2278,7 @@
             if ($i<2) {
                 if (!$headers) {
                     $headers = $this->conn->fetchPartHeader(
-                        $this->mailbox, $this->_msg_id, false, $part->mime_id);
+                        $this->mailbox, $this->_msg_uid, true, $part->mime_id);
                 }
                 $filename_mime = '';
                 $i = 0; $matches = array();
@@ -2396,7 +2297,7 @@
             if ($i<2) {
                 if (!$headers) {
                     $headers = $this->conn->fetchPartHeader(
-                        $this->mailbox, $this->_msg_id, false, $part->mime_id);
+                        $this->mailbox, $this->_msg_uid, true, $part->mime_id);
                 }
                 $filename_encoded = '';
                 $i = 0; $matches = array();
@@ -2465,17 +2366,12 @@
     {
         // get part encoding if not provided
         if (!is_object($o_part)) {
-            $structure_str = $this->conn->fetchStructureString($this->mailbox, $uid, true);
-            $structure = new rcube_mime_struct();
-            // error or message not found
-            if (!$structure->loadStructure($structure_str)) {
-                return false;
-            }
+            $structure = $this->conn->getStructure($this->mailbox, $uid, true);
 
             $o_part = new rcube_message_part;
-            $o_part->ctype_primary = strtolower($structure->getPartType($part));
-            $o_part->encoding      = strtolower($structure->getPartEncoding($part));
-            $o_part->charset       = $structure->getPartCharset($part);
+            $o_part->ctype_primary = strtolower(rcube_imap_generic::getStructurePartType($structure, $part));
+            $o_part->encoding      = strtolower(rcube_imap_generic::getStructurePartEncoding($structure, $part));
+            $o_part->charset       = rcube_imap_generic::getStructurePartCharset($structure, $part);
         }
 
         // TODO: Add caching for message parts
@@ -2584,12 +2480,12 @@
 
         if ($result) {
             // reload message headers if cached
-            if ($this->messages_caching && !$skip_cache) {
-                $cache_key = $mailbox.'.msg';
-                if ($all_mode)
-                    $this->clear_message_cache($cache_key);
-                else
-                    $this->remove_message_cache($cache_key, explode(',', $uids));
+            // @TODO: update flags instead removing from cache
+            if (!$skip_cache && ($mcache = $this->get_mcache_engine())) {
+                $status = strpos($flag, 'UN') !== 0;
+                $mflag  = preg_replace('/^UN/', '', $flag);
+                $mcache->change_flag($mailbox, $all_mode ? null : explode(',', $uids),
+                    $mflag, $status);
             }
 
             // clear cached counters
@@ -2721,19 +2617,18 @@
                 if ($this->search_threads || $all_mode)
                     $this->refresh_search();
                 else {
-                    $uids = explode(',', $uids);
-                    foreach ($uids as $uid)
-                        $a_mids[] = $this->_uid2id($uid, $from_mbox);
+                    $a_uids = explode(',', $uids);
+                    foreach ($a_uids as $uid)
+                        $a_mids[] = $this->uid2id($uid, $from_mbox);
                     $this->search_set = array_diff($this->search_set, $a_mids);
                 }
+                unset($a_mids);
+                unset($a_uids);
             }
 
-            // update cached message headers
-            $cache_key = $from_mbox.'.msg';
-            if ($all_mode || ($start_index = $this->get_message_cache_index_min($cache_key, $uids))) {
-                // clear cache from the lowest index on
-                $this->clear_message_cache($cache_key, $all_mode ? 1 : $start_index);
-            }
+            // remove cached messages
+            // @TODO: do cache update instead of clearing it
+            $this->clear_message_cache($from_mbox, $all_mode ? null : explode(',', $uids));
         }
 
         return $moved;
@@ -2818,19 +2713,17 @@
                 if ($this->search_threads || $all_mode)
                     $this->refresh_search();
                 else {
-                    $uids = explode(',', $uids);
-                    foreach ($uids as $uid)
-                        $a_mids[] = $this->_uid2id($uid, $mailbox);
+                    $a_uids = explode(',', $uids);
+                    foreach ($a_uids as $uid)
+                        $a_mids[] = $this->uid2id($uid, $mailbox);
                     $this->search_set = array_diff($this->search_set, $a_mids);
+                    unset($a_uids);
+                    unset($a_mids);
                 }
             }
 
-            // remove deleted messages from cache
-            $cache_key = $mailbox.'.msg';
-            if ($all_mode || ($start_index = $this->get_message_cache_index_min($cache_key, $uids))) {
-                // clear cache from the lowest index on
-                $this->clear_message_cache($cache_key, $all_mode ? 1 : $start_index);
-            }
+            // remove cached messages
+            $this->clear_message_cache($mailbox, $all_mode ? null : explode(',', $uids));
         }
 
         return $deleted;
@@ -2855,9 +2748,9 @@
             $cleared = $this->conn->clearFolder($mailbox);
         }
 
-        // make sure the message count cache is cleared as well
+        // make sure the cache is cleared as well
         if ($cleared) {
-            $this->clear_message_cache($mailbox.'.msg');
+            $this->clear_message_cache($mailbox);
             $a_mailbox_cache = $this->get_cache('messagecount');
             unset($a_mailbox_cache[$mailbox]);
             $this->update_cache('messagecount', $a_mailbox_cache);
@@ -2898,9 +2791,9 @@
     private function _expunge($mailbox, $clear_cache=true, $uids=NULL)
     {
         if ($uids && $this->get_capability('UIDPLUS'))
-            $a_uids = is_array($uids) ? join(',', $uids) : $uids;
+            list($uids, $all_mode) = $this->_parse_uids($uids, $mailbox);
         else
-            $a_uids = NULL;
+            $uids = null;
 
         // force mailbox selection and check if mailbox is writeable
         // to prevent a situation when CLOSE is executed on closed
@@ -2915,13 +2808,13 @@
         }
 
         // CLOSE(+SELECT) should be faster than EXPUNGE
-        if (empty($a_uids) || $a_uids == '1:*')
+        if (empty($uids) || $all_mode)
             $result = $this->conn->close();
         else
-            $result = $this->conn->expunge($mailbox, $a_uids);
+            $result = $this->conn->expunge($mailbox, $uids);
 
         if ($result && $clear_cache) {
-            $this->clear_message_cache($mailbox.'.msg');
+            $this->clear_message_cache($mailbox, $all_mode ? null : explode(',', $uids));
             $this->_clear_messagecount($mailbox);
         }
 
@@ -2986,7 +2879,7 @@
             $mailbox = $this->mailbox;
         }
 
-        return $this->_uid2id($uid, $mailbox);
+        return $this->uid2id($uid, $mailbox);
     }
 
 
@@ -3004,7 +2897,7 @@
             $mailbox = $this->mailbox;
         }
 
-        return $this->_id2uid($id, $mailbox);
+        return $this->id2uid($id, $mailbox);
     }
 
 
@@ -3302,11 +3195,14 @@
                     $this->conn->unsubscribe($c_subscribed);
                     $this->conn->subscribe(preg_replace('/^'.preg_quote($mailbox, '/').'/',
                         $new_name, $c_subscribed));
+
+                    // clear cache
+                    $this->clear_message_cache($c_subscribed);
                 }
             }
 
             // clear cache
-            $this->clear_message_cache($mailbox.'.msg');
+            $this->clear_message_cache($mailbox);
             $this->clear_cache('mailboxes', true);
         }
 
@@ -3342,13 +3238,13 @@
                 if (preg_match('/^'.preg_quote($mailbox.$delm, '/').'/', $c_mbox)) {
                     $this->conn->unsubscribe($c_mbox);
                     if ($this->conn->deleteFolder($c_mbox)) {
-	                    $this->clear_message_cache($c_mbox.'.msg');
+	                    $this->clear_message_cache($c_mbox);
                     }
                 }
             }
 
             // clear mailbox-related cache
-            $this->clear_message_cache($mailbox.'.msg');
+            $this->clear_message_cache($mailbox);
             $this->clear_cache('mailboxes', true);
         }
 
@@ -3504,6 +3400,36 @@
         $opts = $this->conn->data['LIST'][$mailbox];
 
         return is_array($opts) ? $opts : array();
+    }
+
+
+    /**
+     * Gets connection (and current mailbox) data: UIDVALIDITY, EXISTS, RECENT,
+     * PERMANENTFLAGS, UIDNEXT, UNSEEN
+     *
+     * @param string $mailbox Folder name
+     *
+     * @return array Data
+     */
+    function mailbox_data($mailbox)
+    {
+        if (!strlen($mailbox))
+            $mailbox = $this->mailbox !== null ? $this->mailbox : 'INBOX';
+
+        if ($this->conn->selected != $mailbox) {
+            if ($this->conn->select($mailbox))
+                $this->mailbox = $mailbox;
+        }
+
+        $data = $this->conn->data;
+
+        // add (E)SEARCH result for ALL UNDELETED query
+        if (!empty($this->icache['undeleted_idx']) && $this->icache['undeleted_idx'][0] == $mailbox) {
+            $data['ALL_UNDELETED']   = $this->icache['undeleted_idx'][1];
+            $data['COUNT_UNDELETED'] = $this->icache['undeleted_idx'][2];
+        }
+
+        return $data;
     }
 
 
@@ -3848,7 +3774,7 @@
         else {
             if ($this->cache)
                 $this->cache->close();
-            $this->cache = null;
+            $this->cache   = null;
             $this->caching = false;
         }
     }
@@ -3918,418 +3844,49 @@
      * Enable or disable messages caching
      *
      * @param boolean $set Flag
-     * @access public
      */
     function set_messages_caching($set)
     {
-        $rcmail = rcmail::get_instance();
-
-        if ($set && ($dbh = $rcmail->get_dbh())) {
-            $this->db = $dbh;
+        if ($set) {
             $this->messages_caching = true;
         }
         else {
+            if ($this->mcache)
+                $this->mcache->close();
+            $this->mcache = null;
             $this->messages_caching = false;
         }
     }
 
     /**
-     * Checks if the cache is up-to-date
+     * Getter for messages cache object
+     */
+    private function get_mcache_engine()
+    {
+        if ($this->messages_caching && !$this->mcache) {
+            $rcmail = rcmail::get_instance();
+            if ($dbh = $rcmail->get_dbh()) {
+                $this->mcache = new rcube_imap_cache(
+                    $dbh, $this, $rcmail->user->ID, $this->skip_deleted);
+            }
+        }
+
+        return $this->mcache;
+    }
+
+    /**
+     * Clears the messages cache.
      *
-     * @param string $mailbox   Mailbox name
-     * @param string $cache_key Internal cache key
-     * @return int   Cache status: -3 = off, -2 = incomplete, -1 = dirty, 1 = OK
+     * @param string $mailbox Folder name
+     * @param array  $uids    Optional message UIDs to remove from cache
      */
-    private function check_cache_status($mailbox, $cache_key)
+    function clear_message_cache($mailbox = null, $uids = null)
     {
-        if (!$this->messages_caching)
-            return -3;
-
-        $cache_index = $this->get_message_cache_index($cache_key);
-        $msg_count = $this->_messagecount($mailbox);
-        $cache_count = count($cache_index);
-
-        // empty mailbox
-        if (!$msg_count) {
-            return $cache_count ? -2 : 1;
+        if ($mcache = $this->get_mcache_engine()) {
+            $mcache->clear($mailbox, $uids);
         }
-
-        if ($cache_count == $msg_count) {
-            if ($this->skip_deleted) {
-                if (!empty($this->icache['all_undeleted_idx'])) {
-                    $uids = rcube_imap_generic::uncompressMessageSet($this->icache['all_undeleted_idx']);
-                    $uids = array_flip($uids);
-                    foreach ($cache_index as $uid) {
-                        unset($uids[$uid]);
-                    }
-                }
-                else {
-                    // get all undeleted messages excluding cached UIDs
-                    $uids = $this->search_once($mailbox, 'ALL UNDELETED NOT UID '.
-                        rcube_imap_generic::compressMessageSet($cache_index));
-                }
-                if (empty($uids)) {
-                    return 1;
-                }
-            } else {
-                // get UID of the message with highest index
-                $uid = $this->_id2uid($msg_count, $mailbox);
-                $cache_uid = array_pop($cache_index);
-
-                // uids of highest message matches -> cache seems OK
-                if ($cache_uid == $uid) {
-                    return 1;
-                }
-            }
-            // cache is dirty
-            return -1;
-        }
-
-        // if cache count differs less than 10% report as dirty
-        return (abs($msg_count - $cache_count) < $msg_count/10) ? -1 : -2;
     }
 
-
-    /**
-     * @param string $key Cache key
-     * @param string $from
-     * @param string $to
-     * @param string $sort_field
-     * @param string $sort_order
-     * @access private
-     */
-    private function get_message_cache($key, $from, $to, $sort_field, $sort_order)
-    {
-        if (!$this->messages_caching)
-            return NULL;
-
-        // use idx sort as default sorting
-        if (!$sort_field || !in_array($sort_field, $this->db_header_fields)) {
-            $sort_field = 'idx';
-        }
-
-        $result = array();
-
-        $sql_result = $this->db->limitquery(
-                "SELECT idx, uid, headers".
-                " FROM ".get_table_name('messages').
-                " WHERE user_id=?".
-                " AND cache_key=?".
-                " ORDER BY ".$this->db->quoteIdentifier($sort_field)." ".strtoupper($sort_order),
-                $from,
-                $to - $from,
-                $_SESSION['user_id'],
-                $key);
-
-        while ($sql_arr = $this->db->fetch_assoc($sql_result)) {
-            $uid = intval($sql_arr['uid']);
-            $result[$uid] = $this->db->decode(unserialize($sql_arr['headers']));
-
-            // featch headers if unserialize failed
-            if (empty($result[$uid]))
-                $result[$uid] = $this->conn->fetchHeader(
-                    preg_replace('/.msg$/', '', $key), $uid, true, false, $this->get_fetch_headers());
-        }
-
-        return $result;
-    }
-
-
-    /**
-     * @param string $key Cache key
-     * @param int    $uid Message UID
-     * @return mixed
-     * @access private
-     */
-    private function &get_cached_message($key, $uid)
-    {
-        $internal_key = 'message';
-
-        if ($this->messages_caching && !isset($this->icache[$internal_key][$uid])) {
-            $sql_result = $this->db->query(
-                "SELECT idx, headers, structure, message_id".
-                " FROM ".get_table_name('messages').
-                " WHERE user_id=?".
-                " AND cache_key=?".
-                " AND uid=?",
-                $_SESSION['user_id'],
-                $key,
-                $uid);
-
-            if ($sql_arr = $this->db->fetch_assoc($sql_result)) {
-                $this->icache['message.id'][$uid] = intval($sql_arr['message_id']);
-	            $this->uid_id_map[preg_replace('/\.msg$/', '', $key)][$uid] = intval($sql_arr['idx']);
-                $this->icache[$internal_key][$uid] = $this->db->decode(unserialize($sql_arr['headers']));
-
-                if (is_object($this->icache[$internal_key][$uid]) && !empty($sql_arr['structure']))
-                    $this->icache[$internal_key][$uid]->structure = $this->db->decode(unserialize($sql_arr['structure']));
-            }
-        }
-
-        return $this->icache[$internal_key][$uid];
-    }
-
-
-    /**
-     * @param string  $key        Cache key
-     * @param string  $sort_field Sorting column
-     * @param string  $sort_order Sorting order
-     * @return array Messages index
-     * @access private
-     */
-    private function get_message_cache_index($key, $sort_field='idx', $sort_order='ASC')
-    {
-        if (!$this->messages_caching || empty($key))
-            return NULL;
-
-        // use idx sort as default
-        if (!$sort_field || !in_array($sort_field, $this->db_header_fields))
-            $sort_field = 'idx';
-
-        if (array_key_exists('index', $this->icache)
-            && $this->icache['index']['key'] == $key
-            && $this->icache['index']['sort_field'] == $sort_field
-        ) {
-            if ($this->icache['index']['sort_order'] == $sort_order)
-                return $this->icache['index']['result'];
-            else
-                return array_reverse($this->icache['index']['result'], true);
-        }
-
-        $this->icache['index'] = array(
-            'result'     => array(),
-            'key'        => $key,
-            'sort_field' => $sort_field,
-            'sort_order' => $sort_order,
-        );
-
-        $sql_result = $this->db->query(
-            "SELECT idx, uid".
-            " FROM ".get_table_name('messages').
-            " WHERE user_id=?".
-            " AND cache_key=?".
-            " ORDER BY ".$this->db->quote_identifier($sort_field)." ".$sort_order,
-            $_SESSION['user_id'],
-            $key);
-
-        while ($sql_arr = $this->db->fetch_assoc($sql_result))
-            $this->icache['index']['result'][$sql_arr['idx']] = intval($sql_arr['uid']);
-
-        return $this->icache['index']['result'];
-    }
-
-
-    /**
-     * @access private
-     */
-    private function add_message_cache($key, $index, $headers, $struct=null, $force=false, $internal_cache=false)
-    {
-        if (empty($key) || !is_object($headers) || empty($headers->uid))
-            return;
-
-        // add to internal (fast) cache
-        if ($internal_cache) {
-            $this->icache['message'][$headers->uid] = clone $headers;
-            $this->icache['message'][$headers->uid]->structure = $struct;
-        }
-
-        // no further caching
-        if (!$this->messages_caching)
-            return;
-
-        // known message id
-        if (is_int($force) && $force > 0) {
-            $message_id = $force;
-        }
-        // check for an existing record (probably headers are cached but structure not)
-        else if (!$force) {
-            $sql_result = $this->db->query(
-                "SELECT message_id".
-                " FROM ".get_table_name('messages').
-                " WHERE user_id=?".
-                " AND cache_key=?".
-                " AND uid=?",
-                $_SESSION['user_id'],
-                $key,
-                $headers->uid);
-
-            if ($sql_arr = $this->db->fetch_assoc($sql_result))
-                $message_id = $sql_arr['message_id'];
-        }
-
-        // update cache record
-        if ($message_id) {
-            $this->db->query(
-                "UPDATE ".get_table_name('messages').
-                " SET idx=?, headers=?, structure=?".
-                " WHERE message_id=?",
-                $index,
-                serialize($this->db->encode(clone $headers)),
-                is_object($struct) ? serialize($this->db->encode(clone $struct)) : NULL,
-                $message_id
-            );
-        }
-        else { // insert new record
-            $this->db->query(
-                "INSERT INTO ".get_table_name('messages').
-                " (user_id, del, cache_key, created, idx, uid, subject, ".
-                $this->db->quoteIdentifier('from').", ".
-                $this->db->quoteIdentifier('to').", ".
-                "cc, date, size, headers, structure)".
-                " VALUES (?, 0, ?, ".$this->db->now().", ?, ?, ?, ?, ?, ?, ".
-                $this->db->fromunixtime($headers->timestamp).", ?, ?, ?)",
-                $_SESSION['user_id'],
-                $key,
-                $index,
-                $headers->uid,
-                (string)mb_substr($this->db->encode($this->decode_header($headers->subject, true)), 0, 128),
-                (string)mb_substr($this->db->encode($this->decode_header($headers->from, true)), 0, 128),
-                (string)mb_substr($this->db->encode($this->decode_header($headers->to, true)), 0, 128),
-                (string)mb_substr($this->db->encode($this->decode_header($headers->cc, true)), 0, 128),
-                (int)$headers->size,
-                serialize($this->db->encode(clone $headers)),
-                is_object($struct) ? serialize($this->db->encode(clone $struct)) : NULL
-            );
-        }
-
-        unset($this->icache['index']);
-    }
-
-
-    /**
-     * @access private
-     */
-    private function remove_message_cache($key, $ids, $idx=false)
-    {
-        if (!$this->messages_caching)
-            return;
-
-        $this->db->query(
-            "DELETE FROM ".get_table_name('messages').
-            " WHERE user_id=?".
-            " AND cache_key=?".
-            " AND ".($idx ? "idx" : "uid")." IN (".$this->db->array2list($ids, 'integer').")",
-            $_SESSION['user_id'],
-            $key);
-
-        unset($this->icache['index']);
-    }
-
-
-    /**
-     * @param string $key         Cache key
-     * @param int    $start_index Start index
-     * @access private
-     */
-    private function clear_message_cache($key, $start_index=1)
-    {
-        if (!$this->messages_caching)
-            return;
-
-        $this->db->query(
-            "DELETE FROM ".get_table_name('messages').
-            " WHERE user_id=?".
-            " AND cache_key=?".
-            " AND idx>=?",
-            $_SESSION['user_id'], $key, $start_index);
-
-        unset($this->icache['index']);
-    }
-
-
-    /**
-     * @access private
-     */
-    private function get_message_cache_index_min($key, $uids=NULL)
-    {
-        if (!$this->messages_caching)
-            return;
-
-        if (!empty($uids) && !is_array($uids)) {
-            if ($uids == '*' || $uids == '1:*')
-                $uids = NULL;
-            else
-                $uids = explode(',', $uids);
-        }
-
-        $sql_result = $this->db->query(
-            "SELECT MIN(idx) AS minidx".
-            " FROM ".get_table_name('messages').
-            " WHERE  user_id=?".
-            " AND    cache_key=?"
-            .(!empty($uids) ? " AND uid IN (".$this->db->array2list($uids, 'integer').")" : ''),
-            $_SESSION['user_id'],
-            $key);
-
-        if ($sql_arr = $this->db->fetch_assoc($sql_result))
-            return $sql_arr['minidx'];
-        else
-            return 0;
-    }
-
-
-    /**
-     * @param string $key Cache key
-     * @param int    $id  Message (sequence) ID
-     * @return int Message UID
-     * @access private
-     */
-    private function get_cache_id2uid($key, $id)
-    {
-        if (!$this->messages_caching)
-            return null;
-
-        if (array_key_exists('index', $this->icache)
-            && $this->icache['index']['key'] == $key
-        ) {
-            return $this->icache['index']['result'][$id];
-        }
-
-        $sql_result = $this->db->query(
-            "SELECT uid".
-            " FROM ".get_table_name('messages').
-            " WHERE user_id=?".
-            " AND cache_key=?".
-            " AND idx=?",
-            $_SESSION['user_id'], $key, $id);
-
-        if ($sql_arr = $this->db->fetch_assoc($sql_result))
-            return intval($sql_arr['uid']);
-
-        return null;
-    }
-
-
-    /**
-     * @param string $key Cache key
-     * @param int    $uid Message UID
-     * @return int Message (sequence) ID
-     * @access private
-     */
-    private function get_cache_uid2id($key, $uid)
-    {
-        if (!$this->messages_caching)
-            return null;
-
-        if (array_key_exists('index', $this->icache)
-            && $this->icache['index']['key'] == $key
-        ) {
-            return array_search($uid, $this->icache['index']['result']);
-        }
-
-        $sql_result = $this->db->query(
-            "SELECT idx".
-            " FROM ".get_table_name('messages').
-            " WHERE user_id=?".
-            " AND cache_key=?".
-            " AND uid=?",
-            $_SESSION['user_id'], $key, $uid);
-
-        if ($sql_arr = $this->db->fetch_assoc($sql_result))
-            return intval($sql_arr['idx']);
-
-        return null;
-    }
 
 
     /* --------------------------------
@@ -4627,36 +4184,46 @@
 
 
     /**
-     * @param int    $uid     Message UID
-     * @param string $mailbox Mailbox name
+     * Finds message sequence ID for specified UID
+     *
+     * @param int    $uid      Message UID
+     * @param string $mailbox  Mailbox name
+     * @param bool   $force    True to skip cache
+     *
      * @return int Message (sequence) ID
-     * @access private
      */
-    private function _uid2id($uid, $mailbox=NULL)
+    function uid2id($uid, $mailbox = null, $force = false)
     {
         if (!strlen($mailbox)) {
             $mailbox = $this->mailbox;
         }
 
-        if (!isset($this->uid_id_map[$mailbox][$uid])) {
-            if (!($id = $this->get_cache_uid2id($mailbox.'.msg', $uid)))
-                $id = $this->conn->UID2ID($mailbox, $uid);
-
-            $this->uid_id_map[$mailbox][$uid] = $id;
+        if (!empty($this->uid_id_map[$mailbox][$uid])) {
+            return $this->uid_id_map[$mailbox][$uid];
         }
 
-        return $this->uid_id_map[$mailbox][$uid];
+        if (!$force && ($mcache = $this->get_mcache_engine()))
+            $id = $mcache->uid2id($mailbox, $uid);
+
+        if (empty($id))
+            $id = $this->conn->UID2ID($mailbox, $uid);
+
+        $this->uid_id_map[$mailbox][$uid] = $id;
+
+        return $id;
     }
 
 
     /**
-     * @param int    $id      Message (sequence) ID
-     * @param string $mailbox Mailbox name
+     * Find UID of the specified message sequence ID
+     *
+     * @param int    $id       Message (sequence) ID
+     * @param string $mailbox  Mailbox name
+     * @param bool   $force    True to skip cache
      *
      * @return int Message UID
-     * @access private
      */
-    private function _id2uid($id, $mailbox=null)
+    function id2uid($id, $mailbox = null, $force = false)
     {
         if (!strlen($mailbox)) {
             $mailbox = $this->mailbox;
@@ -4666,9 +4233,11 @@
             return $uid;
         }
 
-        if (!($uid = $this->get_cache_id2uid($mailbox.'.msg', $id))) {
+        if (!$force && ($mcache = $this->get_mcache_engine()))
+            $uid = $mcache->id2uid($mailbox, $id);
+
+        if (empty($uid))
             $uid = $this->conn->ID2UID($mailbox, $id);
-        }
 
         $this->uid_id_map[$mailbox][$uid] = $id;
 
@@ -4954,16 +4523,24 @@
  */
 class rcube_header_sorter
 {
-    var $sequence_numbers = array();
+    private $seqs = array();
+    private $uids = array();
+
 
     /**
      * Set the predetermined sort order.
      *
-     * @param array $seqnums Numerically indexed array of IMAP message sequence numbers
+     * @param array $index  Numerically indexed array of IMAP ID or UIDs
+     * @param bool  $is_uid Set to true if $index contains UIDs
      */
-    function set_sequence_numbers($seqnums)
+    function set_index($index, $is_uid = false)
     {
-        $this->sequence_numbers = array_flip($seqnums);
+        $index = array_flip($index);
+
+        if ($is_uid)
+            $this->uids = $index;
+        else
+            $this->seqs = $index;
     }
 
     /**
@@ -4973,14 +4550,10 @@
      */
     function sort_headers(&$headers)
     {
-        /*
-        * uksort would work if the keys were the sequence number, but unfortunately
-        * the keys are the UIDs.  We'll use uasort instead and dereference the value
-        * to get the sequence number (in the "id" field).
-        *
-        * uksort($headers, array($this, "compare_seqnums"));
-        */
-        uasort($headers, array($this, "compare_seqnums"));
+        if (!empty($this->uids))
+            uksort($headers, array($this, "compare_uids"));
+        else
+            uasort($headers, array($this, "compare_seqnums"));
     }
 
     /**
@@ -4996,8 +4569,24 @@
         $seqb = $b->id;
 
         // then find each sequence number in my ordered list
-        $posa = isset($this->sequence_numbers[$seqa]) ? intval($this->sequence_numbers[$seqa]) : -1;
-        $posb = isset($this->sequence_numbers[$seqb]) ? intval($this->sequence_numbers[$seqb]) : -1;
+        $posa = isset($this->seqs[$seqa]) ? intval($this->seqs[$seqa]) : -1;
+        $posb = isset($this->seqs[$seqb]) ? intval($this->seqs[$seqb]) : -1;
+
+        // return the relative position as the comparison value
+        return $posa - $posb;
+    }
+
+    /**
+     * Sort method called by uksort()
+     *
+     * @param int $a Array key (UID)
+     * @param int $b Array key (UID)
+     */
+    function compare_uids($a, $b)
+    {
+        // then find each sequence number in my ordered list
+        $posa = isset($this->uids[$a]) ? intval($this->uids[$a]) : -1;
+        $posb = isset($this->uids[$b]) ? intval($this->uids[$b]) : -1;
 
         // return the relative position as the comparison value
         return $posa - $posb;
diff --git a/program/include/rcube_imap_cache.php b/program/include/rcube_imap_cache.php
new file mode 100644
index 0000000..f0c3fbb
--- /dev/null
+++ b/program/include/rcube_imap_cache.php
@@ -0,0 +1,907 @@
+<?php
+
+/*
+ +-----------------------------------------------------------------------+
+ | program/include/rcube_imap_cache.php                                  |
+ |                                                                       |
+ | This file is part of the Roundcube Webmail client                     |
+ | Copyright (C) 2005-2011, The Roundcube Dev Team                       |
+ | Licensed under the GNU GPL                                            |
+ |                                                                       |
+ | PURPOSE:                                                              |
+ |   Caching of IMAP folder contents (messages and index)                |
+ |                                                                       |
+ +-----------------------------------------------------------------------+
+ | Author: Thomas Bruederli <roundcube@gmail.com>                        |
+ | Author: Aleksander Machniak <alec@alec.pl>                            |
+ +-----------------------------------------------------------------------+
+
+ $Id$
+
+*/
+
+
+/**
+ * Interface class for accessing Roundcube messages cache
+ *
+ * @package    Cache
+ * @author     Thomas Bruederli <roundcube@gmail.com>
+ * @author     Aleksander Machniak <alec@alec.pl>
+ * @version    1.0
+ */
+class rcube_imap_cache
+{
+    /**
+     * Instance of rcube_imap
+     *
+     * @var rcube_imap
+     */
+    private $imap;
+
+    /**
+     * Instance of rcube_mdb2
+     *
+     * @var rcube_mdb2
+     */
+    private $db;
+
+    /**
+     * User ID
+     *
+     * @var int
+     */
+    private $userid;
+
+    /**
+     * Internal (in-memory) cache
+     *
+     * @var array
+     */
+    private $icache = array();
+
+    private $skip_deleted = false;
+
+    public $flag_fields = array('seen', 'deleted', 'answered', 'forwarded', 'flagged', 'mdnsent');
+
+
+    /**
+     * Object constructor.
+     */
+    function __construct($db, $imap, $userid, $skip_deleted)
+    {
+        $this->db           = $db;
+        $this->imap         = $imap;
+        $this->userid       = (int)$userid;
+        $this->skip_deleted = $skip_deleted;
+    }
+
+
+    /**
+     * Cleanup actions (on shutdown).
+     */
+    public function close()
+    {
+        $this->save_icache();
+        $this->icache = null;
+    }
+
+
+    /**
+     * Return (sorted) messages index.
+     * If index doesn't exist or is invalid, will be updated.
+     *
+     * @param string  $mailbox     Folder name
+     * @param string  $sort_field  Sorting column
+     * @param string  $sort_order  Sorting order (ASC|DESC)
+     * @param bool    $exiting     Skip index initialization if it doesn't exist in DB
+     *
+     * @return array Messages index
+     */
+    function get_index($mailbox, $sort_field = null, $sort_order = null, $existing = false)
+    {
+        if (empty($this->icache[$mailbox]))
+            $this->icache[$mailbox] = array();
+
+        $sort_order = strtoupper($sort_order) == 'ASC' ? 'ASC' : 'DESC';
+
+        // Seek in internal cache
+        if (array_key_exists('index', $this->icache[$mailbox])
+            && ($sort_field == 'ANY' || $this->icache[$mailbox]['index']['sort_field'] == $sort_field)
+        ) {
+            if ($this->icache[$mailbox]['index']['sort_order'] == $sort_order)
+                return $this->icache[$mailbox]['index']['result'];
+            else
+                return array_reverse($this->icache[$mailbox]['index']['result'], true);
+        }
+
+        // Get index from DB (if DB wasn't already queried)
+        if (empty($this->icache[$mailbox]['index_queried'])) {
+            $index = $this->get_index_row($mailbox);
+
+            // set the flag that DB was already queried for index
+            // this way we'll be able to skip one SELECT, when
+            // get_index() is called more than once
+            $this->icache[$mailbox]['index_queried'] = true;
+        }
+        $data  = null;
+
+        // @TODO: Think about skipping validation checks.
+        // If we could check only every 10 minutes, we would be able to skip
+        // expensive checks, mailbox selection or even IMAP connection, this would require
+        // additional logic to force cache invalidation in some cases
+        // and many rcube_imap changes to connect when needed
+
+        // Entry exist, check cache status
+        if (!empty($index)) {
+            $exists = true;
+
+            if ($sort_field == 'ANY') {
+                $sort_field = $index['sort_field'];
+            }
+
+            if ($sort_field != $index['sort_field']) {
+                $is_valid = false;
+            }
+            else {
+                $is_valid = $this->validate($mailbox, $index, $exists);
+            }
+
+            if ($is_valid) {
+                // build index, assign sequence IDs to unique IDs
+                $data = array_combine($index['seq'], $index['uid']);
+                // revert the order if needed
+                if ($index['sort_order'] != $sort_order)
+                    $data = array_reverse($data, true);
+            }
+        }
+        else {
+            // Got it in internal cache, so the row already exist
+            $exists = array_key_exists('index', $this->icache[$mailbox]);
+
+            if ($existing) {
+                return null;
+            }
+            else if ($sort_field == 'ANY') {
+                $sort_field = '';
+            }
+        }
+
+        // Index not found, not valid or sort field changed, get index from IMAP server
+        if ($data === null) {
+            // Get mailbox data (UIDVALIDITY, counters, etc.) for status check
+            $mbox_data = $this->imap->mailbox_data($mailbox);
+            $data      = array();
+
+            // Prevent infinite loop.
+            // It happens when rcube_imap::message_index_direct() is called.
+            // There id2uid() is called which will again call get_index() and so on.
+            if (!$sort_field && !$this->skip_deleted)
+                $this->icache['pending_index_update'] = true;
+
+            if ($mbox_data['EXISTS']) {
+                // fetch sorted sequence numbers
+                $data_seq = $this->imap->message_index_direct($mailbox, $sort_field, $sort_order);
+                // fetch UIDs
+                if (!empty($data_seq)) {
+                    // Seek in internal cache
+                    if (array_key_exists('index', (array)$this->icache[$mailbox]))
+                        $data_uid = $this->icache[$mailbox]['index']['result'];
+                    else
+                        $data_uid = $this->imap->conn->fetchUIDs($mailbox, $data_seq);
+
+                    // build index
+                    if (!empty($data_uid)) {
+                        foreach ($data_seq as $seq)
+                            if ($uid = $data_uid[$seq])
+                                $data[$seq] = $uid;
+                    }
+                }
+            }
+
+            // Reset internal flags
+            $this->icache['pending_index_update'] = false;
+
+            // insert/update
+            $this->add_index_row($mailbox, $sort_field, $sort_order, $data, $mbox_data, $exists);
+        }
+
+        $this->icache[$mailbox]['index'] = array(
+            'result'     => $data,
+            'sort_field' => $sort_field,
+            'sort_order' => $sort_order,
+        );
+
+        return $data;
+    }
+
+
+    /**
+     * Return messages thread.
+     * If threaded index doesn't exist or is invalid, will be updated.
+     *
+     * @param string  $mailbox     Folder name
+     * @param string  $sort_field  Sorting column
+     * @param string  $sort_order  Sorting order (ASC|DESC)
+     *
+     * @return array Messages threaded index
+     */
+    function get_thread($mailbox)
+    {
+        if (empty($this->icache[$mailbox]))
+            $this->icache[$mailbox] = array();
+
+        // Seek in internal cache
+        if (array_key_exists('thread', $this->icache[$mailbox])) {
+            return array(
+                $this->icache[$mailbox]['thread']['tree'],
+                $this->icache[$mailbox]['thread']['depth'],
+                $this->icache[$mailbox]['thread']['children'],
+            );
+        }
+
+        // Get index from DB
+        $index = $this->get_thread_row($mailbox);
+        $data  = null;
+
+        // Entry exist, check cache status
+        if (!empty($index)) {
+            $exists   = true;
+            $is_valid = $this->validate($mailbox, $index, $exists);
+
+            if (!$is_valid) {
+                $index = null;
+            }
+        }
+
+        // Index not found or not valid, get index from IMAP server
+        if ($index === null) {
+            // Get mailbox data (UIDVALIDITY, counters, etc.) for status check
+            $mbox_data = $this->imap->mailbox_data($mailbox);
+
+            if ($mbox_data['EXISTS']) {
+                // get all threads (default sort order)
+                list ($thread_tree, $msg_depth, $has_children) = $this->imap->fetch_threads($mailbox, true);
+            }
+
+            $index = array(
+                'tree'     => !empty($thread_tree) ? $thread_tree : array(),
+                'depth'    => !empty($msg_depth) ? $msg_depth : array(),
+                'children' => !empty($has_children) ? $has_children : array(),
+            );
+
+            // insert/update
+            $this->add_thread_row($mailbox, $index, $mbox_data, $exists);
+        }
+
+        $this->icache[$mailbox]['thread'] = $index;
+
+        return array($index['tree'], $index['depth'], $index['children']);
+    }
+
+
+    /**
+     * Returns list of messages (headers). See rcube_imap::fetch_headers().
+     *
+     * @param string $mailbox  Folder name
+     * @param array  $msgs     Message sequence numbers
+     * @param bool   $is_uid   True if $msgs contains message UIDs
+     *
+     * @return array The list of messages (rcube_mail_header) indexed by UID
+     */
+    function get_messages($mailbox, $msgs = array(), $is_uid = true)
+    {
+        if (empty($msgs)) {
+            return array();
+        }
+
+        // Convert IDs to UIDs
+        // @TODO: it would be nice if we could work with UIDs only
+        // then, e.g. when fetching search result, index would be not needed
+        if (!$is_uid) {
+            $index = $this->get_index($mailbox, 'ANY');
+            foreach ($msgs as $idx => $msgid)
+                if ($uid = $index[$msgid])
+                    $msgs[$idx] = $uid;
+        }
+
+        $flag_fields = implode(', ', array_map(array($this->db, 'quoteIdentifier'), $this->flag_fields));
+
+        // Fetch messages from cache
+        $sql_result = $this->db->query(
+            "SELECT uid, data, ".$flag_fields
+            ." FROM ".get_table_name('cache_messages')
+            ." WHERE user_id = ?"
+                ." AND mailbox = ?"
+                ." AND uid IN (".$this->db->array2list($msgs, 'integer').")",
+            $this->userid, $mailbox);
+
+        $msgs   = array_flip($msgs);
+        $result = array();
+
+        while ($sql_arr = $this->db->fetch_assoc($sql_result)) {
+            $uid          = intval($sql_arr['uid']);
+            $result[$uid] = $this->build_message($sql_arr);
+            // save memory, we don't need a body here
+            $result[$uid]->body = null;
+//@TODO: update message ID according to index data?
+
+            if (!empty($result[$uid])) {
+                unset($msgs[$uid]);
+            }
+        }
+
+        // Fetch not found messages from IMAP server
+        if (!empty($msgs)) {
+            $messages = $this->imap->fetch_headers($mailbox, array_keys($msgs), true, true);
+
+            // Insert to DB and add to result list
+            if (!empty($messages)) {
+                foreach ($messages as $msg) {
+                    $this->add_message($mailbox, $msg, !array_key_exists($msg->uid, $result));
+                    $result[$msg->uid] = $msg;
+                }
+            }
+        }
+
+        return $result;
+    }
+
+
+    /**
+     * Returns message data.
+     *
+     * @param string $mailbox  Folder name
+     * @param int    $uid      Message UID
+     *
+     * @return rcube_mail_header Message data
+     */
+    function get_message($mailbox, $uid)
+    {
+        // Check internal cache
+        if (($message = $this->icache['message'])
+            && $message['mailbox'] == $mailbox && $message['object']->uid == $uid
+        ) {
+            return $this->icache['message']['object'];
+        }
+
+        $flag_fields = implode(', ', array_map(array($this->db, 'quoteIdentifier'), $this->flag_fields));
+
+        $sql_result = $this->db->query(
+            "SELECT data, ".$flag_fields
+            ." FROM ".get_table_name('cache_messages')
+            ." WHERE user_id = ?"
+                ." AND mailbox = ?"
+                ." AND uid = ?",
+                $this->userid, $mailbox, (int)$uid);
+
+        if ($sql_arr = $this->db->fetch_assoc($sql_result)) {
+            $message = $this->build_message($sql_arr);
+            $found   = true;
+
+//@TODO: update message ID according to index data?
+        }
+
+        // Get the message from IMAP server
+        if (empty($message)) {
+            $message = $this->imap->get_headers($uid, $mailbox, true);
+            // cache will be updated in close(), see below
+        }
+
+        // Save the message in internal cache, will be written to DB in close()
+        // Common scenario: user opens unseen message
+        // - get message (SELECT)
+        // - set message headers/structure (INSERT or UPDATE)
+        // - set \Seen flag (UPDATE)
+        // This way we can skip one UPDATE
+        if (!empty($message)) {
+            // Save current message from internal cache
+            $this->save_icache();
+
+            $this->icache['message'] = array(
+                'object'  => $message,
+                'mailbox' => $mailbox,
+                'exists'  => $found,
+                'md5sum'  => md5(serialize($message)),
+            );
+        }
+
+        return $message;
+    }
+
+
+    /**
+     * Saves the message in cache.
+     *
+     * @param string            $mailbox  Folder name
+     * @param rcube_mail_header $message  Message data
+     * @param bool              $force    Skips message in-cache existance check
+     */
+    function add_message($mailbox, $message, $force = false)
+    {
+        if (!is_object($message) || empty($message->uid))
+            return;
+
+        $msg = serialize($this->db->encode(clone $message));
+
+        $flag_fields = array_map(array($this->db, 'quoteIdentifier'), $this->flag_fields);
+        $flag_values = array();
+
+        foreach ($this->flag_fields as $flag)
+            $flag_values[] = (int) $message->$flag;
+
+        // update cache record (even if it exists, the update
+        // here will work as select, assume row exist if affected_rows=0)
+        if (!$force) {
+            foreach ($flag_fields as $key => $val)
+                $flag_data[] = $val . " = " . $flag_values[$key];
+
+            $res = $this->db->query(
+                "UPDATE ".get_table_name('cache_messages')
+                ." SET data = ?, changed = ".$this->db->now()
+                .", " . implode(', ', $flag_data)
+                ." WHERE user_id = ?"
+                    ." AND mailbox = ?"
+                    ." AND uid = ?",
+                $msg, $this->userid, $mailbox, (int) $message->uid);
+
+            if ($this->db->affected_rows())
+                return;
+        }
+
+        // insert new record
+        $this->db->query(
+            "INSERT INTO ".get_table_name('cache_messages')
+            ." (user_id, mailbox, uid, changed, data, " . implode(', ', $flag_fields) . ")"
+            ." VALUES (?, ?, ?, ".$this->db->now().", ?, " . implode(', ', $flag_values) . ")",
+            $this->userid, $mailbox, (int) $message->uid, $msg);
+    }
+
+
+    /**
+     * Sets the flag for specified message.
+     *
+     * @param string  $mailbox  Folder name
+     * @param array   $uids     Message UIDs or null to change flag
+     *                          of all messages in a folder
+     * @param string  $flag     The name of the flag
+     * @param bool    $enabled  Flag state
+     */
+    function change_flag($mailbox, $uids, $flag, $enabled = false)
+    {
+        $flag = strtolower($flag);
+
+        if (in_array($flag, $this->flag_fields)) {
+            // Internal cache update
+            if ($uids && count($uids) == 1 && ($uid = current($uids))
+                && ($message = $this->icache['message'])
+                && $message['mailbox'] == $mailbox && $message['object']->uid == $uid
+            ) {
+                $message['object']->$flag = $enabled;
+                return;
+            }
+
+            $this->db->query(
+                "UPDATE ".get_table_name('cache_messages')
+                ." SET changed = ".$this->db->now()
+                .", " .$this->db->quoteIdentifier($flag) . " = " . intval($enabled)
+                ." WHERE user_id = ?"
+                    ." AND mailbox = ?"
+                    .($uids !== null ? " AND uid IN (".$this->db->array2list((array)$uids, 'integer').")" : ""),
+                $this->userid, $mailbox);
+        }
+        else {
+            // @TODO: SELECT+UPDATE?
+            $this->remove_message($mailbox, $uids);
+        }
+    }
+
+
+    /**
+     * Removes message(s) from cache.
+     *
+     * @param string $mailbox  Folder name
+     * @param array  $uids     Message UIDs, NULL removes all messages
+     */
+    function remove_message($mailbox = null, $uids = null)
+    {
+        if (!strlen($mailbox)) {
+            $this->db->query(
+                "DELETE FROM ".get_table_name('cache_messages')
+                ." WHERE user_id = ?",
+                $this->userid);
+        }
+        else {
+            // Remove the message from internal cache
+            if (!empty($uids) && !is_array($uids) && ($message = $this->icache['message'])
+                && $message['mailbox'] == $mailbox && $message['object']->uid == $uids
+            ) {
+                $this->icache['message'] = null;
+            }
+
+            $this->db->query(
+                "DELETE FROM ".get_table_name('cache_messages')
+                ." WHERE user_id = ?"
+                    ." AND mailbox = ".$this->db->quote($mailbox)
+                    .($uids !== null ? " AND uid IN (".$this->db->array2list((array)$uids, 'integer').")" : ""),
+                $this->userid);
+        }
+
+    }
+
+
+    /**
+     * Clears index cache.
+     *
+     * @param string  $mailbox     Folder name
+     */
+    function remove_index($mailbox = null)
+    {
+        $this->db->query(
+            "DELETE FROM ".get_table_name('cache_index')
+            ." WHERE user_id = ".intval($this->userid)
+                .(strlen($mailbox) ? " AND mailbox = ".$this->db->quote($mailbox) : "")
+        );
+
+        if (strlen($mailbox))
+            unset($this->icache[$mailbox]['index']);
+        else
+            $this->icache = array();
+    }
+
+
+    /**
+     * Clears thread cache.
+     *
+     * @param string  $mailbox     Folder name
+     */
+    function remove_thread($mailbox = null)
+    {
+        $this->db->query(
+            "DELETE FROM ".get_table_name('cache_thread')
+            ." WHERE user_id = ".intval($this->userid)
+                .(strlen($mailbox) ? " AND mailbox = ".$this->db->quote($mailbox) : "")
+        );
+
+        if (strlen($mailbox))
+            unset($this->icache[$mailbox]['thread']);
+        else
+            $this->icache = array();
+    }
+
+
+    /**
+     * Clears the cache.
+     *
+     * @param string $mailbox  Folder name
+     * @param array  $uids     Message UIDs, NULL removes all messages in a folder
+     */
+    function clear($mailbox = null, $uids = null)
+    {
+        $this->remove_index($mailbox);
+        $this->remove_thread($mailbox);
+        $this->remove_message($mailbox, $uids);
+    }
+
+
+    /**
+     * @param string $mailbox Folder name
+     * @param int    $id      Message (sequence) ID
+     *
+     * @return int Message UID
+     */
+    function id2uid($mailbox, $id)
+    {
+        if (!empty($this->icache['pending_index_update']))
+            return null;
+
+        // get index if it exists
+        $index = $this->get_index($mailbox, 'ANY', null, true);
+
+        return $index[$id];
+    }
+
+
+    /**
+     * @param string $mailbox Folder name
+     * @param int    $uid     Message UID
+     *
+     * @return int Message (sequence) ID
+     */
+    function uid2id($mailbox, $uid)
+    {
+        if (!empty($this->icache['pending_index_update']))
+            return null;
+
+        // get index if it exists
+        $index = $this->get_index($mailbox, 'ANY', null, true);
+
+        return array_search($uid, (array)$index);
+    }
+
+
+    /**
+     * Fetches index data from database
+     */
+    private function get_index_row($mailbox)
+    {
+        // Get index from DB
+        $sql_result = $this->db->query(
+            "SELECT data"
+            ." FROM ".get_table_name('cache_index')
+            ." WHERE user_id = ?"
+                ." AND mailbox = ?",
+            $this->userid, $mailbox);
+
+        if ($sql_arr = $this->db->fetch_assoc($sql_result)) {
+            $data = explode('@', $sql_arr['data']);
+
+            return array(
+                'seq'        => explode(',', $data[0]),
+                'uid'        => explode(',', $data[1]),
+                'sort_field' => $data[2],
+                'sort_order' => $data[3],
+                'deleted'    => $data[4],
+                'validity'   => $data[5],
+                'uidnext'    => $data[6],
+            );
+        }
+
+        return null;
+    }
+
+
+    /**
+     * Fetches thread data from database
+     */
+    private function get_thread_row($mailbox)
+    {
+        // Get thread from DB
+        $sql_result = $this->db->query(
+            "SELECT data"
+            ." FROM ".get_table_name('cache_thread')
+            ." WHERE user_id = ?"
+                ." AND mailbox = ?",
+            $this->userid, $mailbox);
+
+        if ($sql_arr = $this->db->fetch_assoc($sql_result)) {
+            $data = explode('@', $sql_arr['data']);
+
+            $data[0] = unserialize($data[0]);
+            // build 'depth' and 'children' arrays
+            $depth = $children = array();
+            $this->build_thread_data($data[0], $depth, $children);
+
+            return array(
+                'tree'     => $data[0],
+                'depth'    => $depth,
+                'children' => $children,
+                'deleted'  => $data[1],
+                'validity' => $data[2],
+                'uidnext'  => $data[3],
+            );
+        }
+
+        return null;
+    }
+
+
+    /**
+     * Saves index data into database
+     */
+    private function add_index_row($mailbox, $sort_field, $sort_order,
+        $data = array(), $mbox_data = array(), $exists = false)
+    {
+        $data = array(
+            implode(',', array_keys($data)),
+            implode(',', array_values($data)),
+            $sort_field,
+            $sort_order,
+            (int) $this->skip_deleted,
+            (int) $mbox_data['UIDVALIDITY'],
+            (int) $mbox_data['UIDNEXT'],
+        );
+        $data = implode('@', $data);
+
+        if ($exists)
+            $sql_result = $this->db->query(
+                "UPDATE ".get_table_name('cache_index')
+                ." SET data = ?, changed = ".$this->db->now()
+                ." WHERE user_id = ?"
+                    ." AND mailbox = ?",
+                $data, $this->userid, $mailbox);
+        else
+            $sql_result = $this->db->query(
+                "INSERT INTO ".get_table_name('cache_index')
+                ." (user_id, mailbox, data, changed)"
+                ." VALUES (?, ?, ?, ".$this->db->now().")",
+                $this->userid, $mailbox, $data);
+    }
+
+
+    /**
+     * Saves thread data into database
+     */
+    private function add_thread_row($mailbox, $data = array(), $mbox_data = array(), $exists = false)
+    {
+        $data = array(
+            serialize($data['tree']),
+            (int) $this->skip_deleted,
+            (int) $mbox_data['UIDVALIDITY'],
+            (int) $mbox_data['UIDNEXT'],
+        );
+        $data = implode('@', $data);
+
+        if ($exists)
+            $sql_result = $this->db->query(
+                "UPDATE ".get_table_name('cache_thread')
+                ." SET data = ?, changed = ".$this->db->now()
+                ." WHERE user_id = ?"
+                    ." AND mailbox = ?",
+                $data, $this->userid, $mailbox);
+        else
+            $sql_result = $this->db->query(
+                "INSERT INTO ".get_table_name('cache_thread')
+                ." (user_id, mailbox, data, changed)"
+                ." VALUES (?, ?, ?, ".$this->db->now().")",
+                $this->userid, $mailbox, $data);
+    }
+
+
+    /**
+     * Checks index/thread validity
+     */
+    private function validate($mailbox, $index, &$exists = true)
+    {
+        $is_thread = isset($index['tree']);
+
+        // Get mailbox data (UIDVALIDITY, counters, etc.) for status check
+        $mbox_data = $this->imap->mailbox_data($mailbox);
+
+        // @TODO: Think about skipping validation checks.
+        // If we could check only every 10 minutes, we would be able to skip
+        // expensive checks, mailbox selection or even IMAP connection, this would require
+        // additional logic to force cache invalidation in some cases
+        // and many rcube_imap changes to connect when needed
+
+        // Check UIDVALIDITY
+        // @TODO: while we're storing message sequence numbers in thread
+        //        index, should UIDVALIDITY invalidate the thread data?
+        if ($index['validity'] != $mbox_data['UIDVALIDITY']) {
+            // the whole cache (all folders) is invalid
+            $this->clear();
+            $exists = false;
+            return false;
+        }
+
+        // Folder is empty but cache isn't
+        if (empty($mbox_data['EXISTS']) && (!empty($index['seq']) || !empty($index['tree']))) {
+            $this->clear($mailbox);
+            $exists = false;
+            return false;
+        }
+
+        // Check UIDNEXT
+        if ($index['uidnext'] != $mbox_data['UIDNEXT']) {
+            unset($this->icache[$mailbox][$is_thread ? 'thread' : 'index']);
+            return false;
+        }
+
+        // Index was created with different skip_deleted setting
+        if ($this->skip_deleted != $index['deleted']) {
+            return false;
+        }
+
+        // @TODO: find better validity check for threaded index
+        if ($is_thread) {
+            // check messages number...
+            if ($mbox_data['EXISTS'] != max(array_keys($index['depth']))) {
+                return false;
+            }
+            return true;
+        }
+
+        // The rest of checks, more expensive
+        if (!empty($this->skip_deleted)) {
+            // compare counts if available
+            if ($mbox_data['COUNT_UNDELETED'] != null
+                && $mbox_data['COUNT_UNDELETED'] != count($index['uid'])) {
+                return false;
+            }
+            // compare UID sets
+            if ($mbox_data['ALL_UNDELETED'] != null) {
+                $uids_new = rcube_imap_generic::uncompressMessageSet($mbox_data['ALL_UNDELETED']);
+                $uids_old = $index['uid'];
+
+                if (count($uids_new) != count($uids_old)) {
+                    return false;
+                }
+
+                sort($uids_new, SORT_NUMERIC);
+                sort($uids_old, SORT_NUMERIC);
+
+                if ($uids_old != $uids_new)
+                    return false;
+            }
+            else {
+                // get all undeleted messages excluding cached UIDs
+                $ids = $this->imap->search_once($mailbox, 'ALL UNDELETED NOT UID '.
+                    rcube_imap_generic::compressMessageSet($index['uid']));
+
+                if (!empty($ids)) {
+                    $index = null; // cache invalid
+                }
+            }
+        }
+        else {
+            // check messages number...
+            if ($mbox_data['EXISTS'] != max($index['seq'])) {
+                return false;
+            }
+            // ... and max UID
+            if (max($index['uid']) != $this->imap->id2uid($mbox_data['EXISTS'], $mailbox, true)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+
+    /**
+     * Converts cache row into message object.
+     *
+     * @param array $sql_arr Message row data
+     *
+     * @return rcube_mail_header Message object
+     */
+    private function build_message($sql_arr)
+    {
+        $message = $this->db->decode(unserialize($sql_arr['data']));
+
+        if ($message) {
+            foreach ($this->flag_fields as $field)
+                $message->$field = (bool) $sql_arr[$field];
+        }
+
+        return $message;
+    }
+
+
+    /**
+     * Creates 'depth' and 'children' arrays from stored thread 'tree' data.
+     */
+    private function build_thread_data($data, &$depth, &$children, $level = 0)
+    {
+        foreach ((array)$data as $key => $val) {
+            $children[$key] = !empty($val);
+            $depth[$key] = $level;
+            if (!empty($val))
+                $this->build_thread_data($val, $depth, $children, $level + 1);
+        }
+    }
+
+
+    /**
+     * Saves message stored in internal cache
+     */
+    private function save_icache()
+    {
+        // Save current message from internal cache
+        if ($message = $this->icache['message']) {
+            $object = $message['object'];
+            // remove body too big (>500kB)
+            if ($object->body && strlen($object->body) > 500 * 1024)
+                $object->body = null;
+
+            // calculate current md5 sum
+            $md5sum = md5(serialize($object));
+
+            if ($message['md5sum'] != $md5sum) {
+                $this->add_message($message['mailbox'], $object, !$message['exists']);
+            }
+
+            $this->icache['message']['md5sum'] = $md5sum;
+        }
+    }
+
+}
diff --git a/program/include/rcube_imap_generic.php b/program/include/rcube_imap_generic.php
index 75acc5a..65b2025 100644
--- a/program/include/rcube_imap_generic.php
+++ b/program/include/rcube_imap_generic.php
@@ -48,22 +48,20 @@
     public $encoding;
     public $charset;
     public $ctype;
-    public $flags;
     public $timestamp;
-    public $body_structure;
+    public $bodystructure;
     public $internaldate;
     public $references;
     public $priority;
     public $mdn_to;
-    public $mdn_sent = false;
+
+    public $flags;
+    public $mdnsent = false;
     public $seen = false;
     public $deleted = false;
     public $answered = false;
     public $forwarded = false;
     public $flagged = false;
-    public $has_children = false;
-    public $depth = 0;
-    public $unread_children = 0;
     public $others = array();
 }
 
@@ -84,6 +82,7 @@
     public $errornum;
     public $result;
     public $resultcode;
+    public $selected;
     public $data = array();
     public $flags = array(
         'SEEN'     => '\\Seen',
@@ -96,7 +95,6 @@
         '*'        => '\\*',
     );
 
-    private $selected;
     private $fp;
     private $host;
     private $logged = false;
@@ -235,14 +233,14 @@
         return $line;
     }
 
-    function multLine($line, $escape=false)
+    function multLine($line, $escape = false)
     {
         $line = rtrim($line);
-        if (preg_match('/\{[0-9]+\}$/', $line)) {
-            $out = '';
+        if (preg_match('/\{([0-9]+)\}$/', $line, $m)) {
+            $out   = '';
+            $str   = substr($line, 0, -strlen($m[0]));
+            $bytes = $m[1];
 
-            preg_match_all('/(.*)\{([0-9]+)\}$/', $line, $a);
-            $bytes = $a[2][0];
             while (strlen($out) < $bytes) {
                 $line = $this->readBytes($bytes);
                 if ($line === NULL)
@@ -250,7 +248,7 @@
                 $out .= $line;
             }
 
-            $line = $a[1][0] . ($escape ? $this->escape($out) : $out);
+            $line = $str . ($escape ? $this->escape($out) : $out);
         }
 
         return $line;
@@ -877,12 +875,12 @@
     /**
      * Executes SELECT command (if mailbox is already not in selected state)
      *
-     * @param string $mailbox Mailbox name
+     * @param string $mailbox      Mailbox name
+     * @param array  $qresync_data QRESYNC data (RFC5162)
      *
      * @return boolean True on success, false on error
-     * @access public
      */
-    function select($mailbox)
+    function select($mailbox, $qresync_data = null)
     {
         if (!strlen($mailbox)) {
             return false;
@@ -901,7 +899,21 @@
             }
         }
 */
-        list($code, $response) = $this->execute('SELECT', array($this->escape($mailbox)));
+        $params = array($this->escape($mailbox));
+
+        // QRESYNC data items
+        //    0. the last known UIDVALIDITY,
+        //    1. the last known modification sequence,
+        //    2. the optional set of known UIDs, and
+        //    3. an optional parenthesized list of known sequence ranges and their
+        //       corresponding UIDs.
+        if (!empty($qresync_data)) {
+            if (!empty($qresync_data[2]))
+                $qresync_data[2] = self::compressMessageSet($qresync_data[2]);
+            $params[] = array('QRESYNC', $qresync_data);
+        }
+
+        list($code, $response) = $this->execute('SELECT', $params);
 
         if ($code == self::ERROR_OK) {
             $response = explode("\r\n", $response);
@@ -909,11 +921,39 @@
                 if (preg_match('/^\* ([0-9]+) (EXISTS|RECENT)$/i', $line, $m)) {
                     $this->data[strtoupper($m[2])] = (int) $m[1];
                 }
-                else if (preg_match('/^\* OK \[(UIDNEXT|UIDVALIDITY|UNSEEN) ([0-9]+)\]/i', $line, $match)) {
-                    $this->data[strtoupper($match[1])] = (int) $match[2];
+                else if (preg_match('/^\* OK \[/i', $line, $match)) {
+                    $line = substr($line, 6);
+                    if (preg_match('/^(UIDNEXT|UIDVALIDITY|UNSEEN) ([0-9]+)/i', $line, $match)) {
+                        $this->data[strtoupper($match[1])] = (int) $match[2];
+                    }
+                    else if (preg_match('/^(HIGHESTMODSEQ) ([0-9]+)/i', $line, $match)) {
+                        $this->data[strtoupper($match[1])] = (string) $match[2];
+                    }
+                    else if (preg_match('/^(NOMODSEQ)/i', $line, $match)) {
+                        $this->data[strtoupper($match[1])] = true;
+                    }
+                    else if (preg_match('/^PERMANENTFLAGS \(([^\)]+)\)/iU', $line, $match)) {
+                        $this->data['PERMANENTFLAGS'] = explode(' ', $match[1]);
+                    }
                 }
-                else if (preg_match('/^\* OK \[PERMANENTFLAGS \(([^\)]+)\)\]/iU', $line, $match)) {
-                    $this->data['PERMANENTFLAGS'] = explode(' ', $match[1]);
+                // QRESYNC FETCH response (RFC5162)
+                else if (preg_match('/^\* ([0-9+]) FETCH/i', $line, $match)) {
+                    $line       = substr($line, strlen($match[0]));
+                    $fetch_data = $this->tokenizeResponse($line, 1);
+                    $data       = array('id' => $match[1]);
+
+                    for ($i=0, $size=count($fetch_data); $i<$size; $i+=2) {
+                        $data[strtolower($fetch_data[$i])] = $fetch_data[$i+1];
+                    }
+
+                    $this->data['QRESYNC'][$data['uid']] = $data;
+                }
+                // QRESYNC VANISHED response (RFC5162)
+                else if (preg_match('/^\* VANISHED [()EARLIER]*/i', $line, $match)) {
+                    $line   = substr($line, strlen($match[0]));
+                    $v_data = $this->tokenizeResponse($line, 1);
+
+                    $this->data['VANISHED'] = $v_data;
                 }
             }
 
@@ -935,7 +975,6 @@
      *                        in RFC3501: UIDNEXT, UIDVALIDITY, RECENT
      *
      * @return array Status item-value hash
-     * @access public
      * @since 0.5-beta
      */
     function status($mailbox, $items=array())
@@ -971,7 +1010,7 @@
             }
 
             for ($i=0, $len=count($items); $i<$len; $i += 2) {
-                $result[$items[$i]] = (int) $items[$i+1];
+                $result[$items[$i]] = $items[$i+1];
             }
 
             $this->data['STATUS:'.$mailbox] = $result;
@@ -989,7 +1028,6 @@
      * @param string $messages Message UIDs to expunge
      *
      * @return boolean True on success, False on error
-     * @access public
      */
     function expunge($mailbox, $messages=NULL)
     {
@@ -1022,7 +1060,6 @@
      * Executes CLOSE command
      *
      * @return boolean True on success, False on error
-     * @access public
      * @since 0.5
      */
     function close()
@@ -1043,7 +1080,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return boolean True on success, False on error
-     * @access public
      */
     function subscribe($mailbox)
     {
@@ -1059,7 +1095,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return boolean True on success, False on error
-     * @access public
      */
     function unsubscribe($mailbox)
     {
@@ -1075,7 +1110,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return boolean True on success, False on error
-     * @access public
      */
     function deleteFolder($mailbox)
     {
@@ -1091,7 +1125,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return boolean True on success, False on error
-     * @access public
      */
     function clearFolder($mailbox)
     {
@@ -1116,7 +1149,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return int Number of messages, False on error
-     * @access public
      */
     function countMessages($mailbox, $refresh = false)
     {
@@ -1149,7 +1181,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return int Number of messages, False on error
-     * @access public
      */
     function countRecent($mailbox)
     {
@@ -1172,7 +1203,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return int Number of messages, False on error
-     * @access public
      */
     function countUnseen($mailbox)
     {
@@ -1203,7 +1233,6 @@
      * @param array $items Client identification information key/value hash
      *
      * @return array Server identification information key/value hash
-     * @access public
      * @since 0.6
      */
     function id($items=array())
@@ -1228,6 +1257,37 @@
             for ($i=0, $len=count($items); $i<$len; $i += 2) {
                 $result[$items[$i]] = $items[$i+1];
             }
+
+            return $result;
+        }
+
+        return false;
+    }
+
+    /**
+     * Executes ENABLE command (RFC5161)
+     *
+     * @param mixed $extension Extension name to enable (or array of names)
+     *
+     * @return array|bool List of enabled extensions, False on error
+     * @since 0.6
+     */
+    function enable($extension)
+    {
+        if (empty($extension))
+            return false;
+
+        if (!$this->hasCapability('ENABLE'))
+            return false;
+
+        if (!is_array($extension))
+            $extension = array($extension);
+
+        list($code, $response) = $this->execute('ENABLE', $extension);
+
+        if ($code == self::ERROR_OK && preg_match('/\* ENABLED /i', $response)) {
+            $response = substr($response, 10); // remove prefix "* ENABLED "
+            $result   = (array) $this->tokenizeResponse($response);
 
             return $result;
         }
@@ -1472,7 +1532,6 @@
      * @param int    $uid     Message unique identifier (UID)
      *
      * @return int Message sequence identifier
-     * @access public
      */
     function UID2ID($mailbox, $uid)
     {
@@ -1492,12 +1551,11 @@
      * @param int    $uid     Message sequence identifier
      *
      * @return int Message unique identifier
-     * @access public
      */
     function ID2UID($mailbox, $id)
     {
         if (empty($id) || $id < 0) {
-            return 	null;
+            return null;
         }
 
         if (!$this->select($mailbox)) {
@@ -1515,46 +1573,58 @@
 
     function fetchUIDs($mailbox, $message_set=null)
     {
-        if (is_array($message_set))
-            $message_set = join(',', $message_set);
-        else if (empty($message_set))
+        if (empty($message_set))
             $message_set = '1:*';
 
         return $this->fetchHeaderIndex($mailbox, $message_set, 'UID', false);
     }
 
-    function fetchHeaders($mailbox, $message_set, $uidfetch=false, $bodystr=false, $add='')
+    /**
+     * FETCH command (RFC3501)
+     *
+     * @param string $mailbox     Mailbox name
+     * @param mixed  $message_set Message(s) sequence identifier(s) or UID(s)
+     * @param bool   $is_uid      True if $message_set contains UIDs
+     * @param array  $query_items FETCH command data items
+     * @param string $mod_seq     Modification sequence for CHANGEDSINCE (RFC4551) query
+     * @param bool   $vanished    Enables VANISHED parameter (RFC5162) for CHANGEDSINCE query
+     *
+     * @return array List of rcube_mail_header elements, False on error
+     * @since 0.6
+     */
+    function fetch($mailbox, $message_set, $is_uid = false, $query_items = array(),
+        $mod_seq = null, $vanished = false)
     {
-        $result = array();
-
         if (!$this->select($mailbox)) {
             return false;
         }
 
         $message_set = $this->compressMessageSet($message_set);
+        $result      = array();
 
-        if ($add)
-            $add = ' '.trim($add);
-
-        /* FETCH uid, size, flags and headers */
         $key      = $this->nextTag();
-        $request  = $key . ($uidfetch ? ' UID' : '') . " FETCH $message_set ";
-        $request .= "(UID RFC822.SIZE FLAGS INTERNALDATE ";
-        if ($bodystr)
-            $request .= "BODYSTRUCTURE ";
-        $request .= "BODY.PEEK[HEADER.FIELDS (DATE FROM TO SUBJECT CONTENT-TYPE ";
-        $request .= "CC REPLY-TO LIST-POST DISPOSITION-NOTIFICATION-TO X-PRIORITY".$add.")])";
+        $request  = $key . ($is_uid ? ' UID' : '') . " FETCH $message_set ";
+        $request .= "(" . implode(' ', $query_items) . ")";
+
+        if ($mod_seq !== null && $this->hasCapability('CONDSTORE')) {
+            $request .= " (CHANGEDSINCE $mod_seq" . ($vanished ? " VANISHED" : '') .")";
+        }
 
         if (!$this->putLine($request)) {
             $this->setError(self::ERROR_COMMAND, "Unable to send command: $request");
             return false;
         }
+
         do {
             $line = $this->readLine(4096);
-            $line = $this->multLine($line);
 
             if (!$line)
                 break;
+
+            // Sample reply line:
+            // * 321 FETCH (UID 2417 RFC822.SIZE 2730 FLAGS (\Seen)
+            // INTERNALDATE "16-Nov-2008 21:08:46 +0100" BODYSTRUCTURE (...)
+            // BODY[HEADER.FIELDS ...
 
             if (preg_match('/^\* ([0-9]+) FETCH/', $line, $m)) {
                 $id = intval($m[1]);
@@ -1565,101 +1635,112 @@
                 $result[$id]->messageID = 'mid:' . $id;
 
                 $lines = array();
-                $ln = 0;
+                $line  = substr($line, strlen($m[0]) + 2);
+                $ln    = 0;
 
-                // Sample reply line:
-                // * 321 FETCH (UID 2417 RFC822.SIZE 2730 FLAGS (\Seen)
-                // INTERNALDATE "16-Nov-2008 21:08:46 +0100" BODYSTRUCTURE (...)
-                // BODY[HEADER.FIELDS ...
+                // get complete entry
+                while (preg_match('/\{([0-9]+)\}\r\n$/', $line, $m)) {
+                    $bytes = $m[1];
+                    $out   = '';
 
-                if (preg_match('/^\* [0-9]+ FETCH \((.*) BODY/sU', $line, $matches)) {
-                    $str = $matches[1];
-
-                    while (list($name, $value) = $this->tokenizeResponse($str, 2)) {
-                        if ($name == 'UID') {
-                            $result[$id]->uid = intval($value);
-                        }
-                        else if ($name == 'RFC822.SIZE') {
-                            $result[$id]->size = intval($value);
-                        }
-                        else if ($name == 'INTERNALDATE') {
-                            $result[$id]->internaldate = $value;
-                            $result[$id]->date         = $value;
-                            $result[$id]->timestamp    = $this->StrToTime($value);
-                        }
-                        else if ($name == 'FLAGS') {
-                            $flags_a = $value;
-                        }
+                    while (strlen($out) < $bytes) {
+                        $out = $this->readBytes($bytes);
+                        if ($out === NULL)
+                            break;
+                        $line .= $out;
                     }
 
-                    // BODYSTRUCTURE
-                    if ($bodystr) {
-                        while (!preg_match('/ BODYSTRUCTURE (.*) BODY\[HEADER.FIELDS/sU', $line, $m)) {
-                            $line2 = $this->readLine(1024);
-                            $line .= $this->multLine($line2, true);
-                        }
-                        $result[$id]->body_structure = $m[1];
-                    }
+                    $str = $this->readLine(4096);
+                    if ($str === false)
+                        break;
 
-                    // the rest of the result
-                    if (preg_match('/ BODY\[HEADER.FIELDS \(.*?\)\]\s*(.*)$/s', $line, $m)) {
-                        $reslines = explode("\n", trim($m[1], '"'));
-                        // re-parse (see below)
-                        foreach ($reslines as $resln) {
-                            if (ord($resln[0])<=32) {
-                                $lines[$ln] .= (empty($lines[$ln])?'':"\n").trim($resln);
-                            } else {
-                                $lines[++$ln] = trim($resln);
+                    $line .= $str;
+                }
+
+                // Tokenize response and assign to object properties
+                while (list($name, $value) = $this->tokenizeResponse($line, 2)) {
+                    if ($name == 'UID') {
+                        $result[$id]->uid = intval($value);
+                    }
+                    else if ($name == 'RFC822.SIZE') {
+                        $result[$id]->size = intval($value);
+                    }
+                    else if ($name == 'RFC822.TEXT') {
+                        $result[$id]->body = $value;
+                    }
+                    else if ($name == 'INTERNALDATE') {
+                        $result[$id]->internaldate = $value;
+                        $result[$id]->date         = $value;
+                        $result[$id]->timestamp    = $this->StrToTime($value);
+                    }
+                    else if ($name == 'FLAGS') {
+                        if (!empty($value)) {
+                            foreach ((array)$value as $flag) {
+                                $flag = str_replace('\\', '', $flag);
+
+                                switch (strtoupper($flag)) {
+                                case 'SEEN':
+                                    $result[$id]->seen = true;
+                                    break;
+                                case 'DELETED':
+                                    $result[$id]->deleted = true;
+                                    break;
+                                case 'ANSWERED':
+                                    $result[$id]->answered = true;
+                                    break;
+                                case '$FORWARDED':
+                                    $result[$id]->forwarded = true;
+                                    break;
+                                case '$MDNSENT':
+                                    $result[$id]->mdnsent = true;
+                                    break;
+                                case 'FLAGGED':
+                                    $result[$id]->flagged = true;
+                                    break;
+                                default:
+                                    $result[$id]->flags[] = $flag;
+                                    break;
+                                }
                             }
                         }
                     }
+                    else if ($name == 'MODSEQ') {
+                        $result[$id]->modseq = $value[0];
+                    }
+                    else if ($name == 'ENVELOPE') {
+                        $result[$id]->envelope = $value;
+                    }
+                    else if ($name == 'BODYSTRUCTURE' || ($name == 'BODY' && count($value) > 2)) {
+                        if (!is_array($value[0]) && (strtolower($value[0]) == 'message' && strtolower($value[1]) == 'rfc822')) {
+                            $value = array($value);
+                        }
+                        $result[$id]->bodystructure = $value;
+                    }
+                    else if ($name == 'RFC822') {
+                        $result[$id]->body = $value;
+                    }
+                    else if ($name == 'BODY') {
+                        $body = $this->tokenizeResponse($line, 1);
+                        if ($value[0] == 'HEADER.FIELDS')
+                            $headers = $body;
+                        else if (!empty($value))
+                            $result[$id]->bodypart[$value[0]] = $body;
+                        else
+                            $result[$id]->body = $body;
+                    }
                 }
 
-                // Start parsing headers.  The problem is, some header "lines" take up multiple lines.
-                // So, we'll read ahead, and if the one we're reading now is a valid header, we'll
-                // process the previous line.  Otherwise, we'll keep adding the strings until we come
-                // to the next valid header line.
-
-                do {
-                    $line = rtrim($this->readLine(300), "\r\n");
-
-                    // The preg_match below works around communigate imap, which outputs " UID <number>)".
-                    // Without this, the while statement continues on and gets the "FH0 OK completed" message.
-                    // If this loop gets the ending message, then the outer loop does not receive it from radline on line 1249.
-                    // This in causes the if statement on line 1278 to never be true, which causes the headers to end up missing
-                    // If the if statement was changed to pick up the fh0 from this loop, then it causes the outer loop to spin
-                    // An alternative might be:
-                    // if (!preg_match("/:/",$line) && preg_match("/\)$/",$line)) break;
-                    // however, unsure how well this would work with all imap clients.
-                    if (preg_match("/^\s*UID [0-9]+\)$/", $line)) {
-                        break;
-                    }
-
-                    // handle FLAGS reply after headers (AOL, Zimbra?)
-                    if (preg_match('/\s+FLAGS \((.*)\)\)$/', $line, $matches)) {
-                        $flags_a = $this->tokenizeResponse($matches[1]);
-                        break;
-                    }
-
-                    if (ord($line[0])<=32) {
-                        $lines[$ln] .= (empty($lines[$ln])?'':"\n").trim($line);
-                    } else {
-                        $lines[++$ln] = trim($line);
-                    }
-                // patch from "Maksim Rubis" <siburny@hotmail.com>
-                } while ($line[0] != ')' && !$this->startsWith($line, $key, true));
-
-                if (strncmp($line, $key, strlen($key))) {
-                    // process header, fill rcube_mail_header obj.
-                    // initialize
-                    if (is_array($headers)) {
-                        reset($headers);
-                        while (list($k, $bar) = each($headers)) {
-                            $headers[$k] = '';
+                // create array with header field:data
+                if (!empty($headers)) {
+                    $headers = explode("\n", trim($headers));
+                    foreach ($headers as $hid => $resln) {
+                        if (ord($resln[0]) <= 32) {
+                            $lines[$ln] .= (empty($lines[$ln]) ? '' : "\n") . trim($resln);
+                        } else {
+                            $lines[++$ln] = trim($resln);
                         }
                     }
 
-                    // create array with header field:data
                     while (list($lines_key, $str) = each($lines)) {
                         list($field, $string) = explode(':', $str, 2);
 
@@ -1723,47 +1804,44 @@
                                 $result[$id]->others[$field] = $string;
                             }
                             break;
-                        } // end switch ()
-                    } // end while ()
-                }
-
-                // process flags
-                if (!empty($flags_a)) {
-                    foreach ($flags_a as $flag) {
-                        $flag = str_replace('\\', '', $flag);
-                        $result[$id]->flags[] = $flag;
-
-                        switch (strtoupper($flag)) {
-                        case 'SEEN':
-                            $result[$id]->seen = true;
-                            break;
-                        case 'DELETED':
-                            $result[$id]->deleted = true;
-                            break;
-                        case 'ANSWERED':
-                            $result[$id]->answered = true;
-                            break;
-                        case '$FORWARDED':
-                            $result[$id]->forwarded = true;
-                            break;
-                        case '$MDNSENT':
-                            $result[$id]->mdn_sent = true;
-                            break;
-                        case 'FLAGGED':
-                            $result[$id]->flagged = true;
-                            break;
                         }
                     }
                 }
             }
+
+            // VANISHED response (QRESYNC RFC5162)
+            // Sample: * VANISHED (EARLIER) 300:310,405,411
+
+            else if (preg_match('/^\* VANISHED [EARLIER]*/i', $line, $match)) {
+                $line   = substr($line, strlen($match[0]));
+                $v_data = $this->tokenizeResponse($line, 1);
+
+                $this->data['VANISHED'] = $v_data;
+            }
+
         } while (!$this->startsWith($line, $key, true));
+
+        return $result;
+    }
+
+    function fetchHeaders($mailbox, $message_set, $is_uid = false, $bodystr = false, $add = '')
+    {
+        $query_items = array('UID', 'RFC822.SIZE', 'FLAGS', 'INTERNALDATE');
+        if ($bodystr)
+            $query_items[] = 'BODYSTRUCTURE';
+        $query_items[] = 'BODY.PEEK[HEADER.FIELDS ('
+            . 'DATE FROM TO SUBJECT CONTENT-TYPE CC REPLY-TO LIST-POST DISPOSITION-NOTIFICATION-TO X-PRIORITY'
+            . ($add ? ' ' . trim($add) : '')
+            . ')]';
+
+        $result = $this->fetch($mailbox, $message_set, $is_uid, $query_items);
 
         return $result;
     }
 
     function fetchHeader($mailbox, $id, $uidfetch=false, $bodystr=false, $add='')
     {
-        $a  = $this->fetchHeaders($mailbox, $id, $uidfetch, $bodystr, $add);
+        $a = $this->fetchHeaders($mailbox, $id, $uidfetch, $bodystr, $add);
         if (is_array($a)) {
             return array_shift($a);
         }
@@ -2043,6 +2121,7 @@
             $params .= 'RETURN (' . implode(' ', $items) . ')';
         }
         if (!empty($criteria)) {
+            $modseq = stripos($criteria, 'MODSEQ') !== false;
             $params .= ($params ? ' ' : '') . $criteria;
         }
         else {
@@ -2054,11 +2133,18 @@
 
         if ($code == self::ERROR_OK) {
             // remove prefix...
-            $response = substr($response, stripos($response, 
+            $response = substr($response, stripos($response,
                 $esearch ? '* ESEARCH' : '* SEARCH') + ($esearch ? 10 : 9));
             // ...and unilateral untagged server responses
             if ($pos = strpos($response, '*')) {
                 $response = rtrim(substr($response, 0, $pos));
+            }
+
+            // remove MODSEQ response
+            if ($modseq) {
+                if (preg_match('/\(MODSEQ ([0-9]+)\)$/', $response, $m)) {
+                    $response = substr($response, 0, -strlen($m[0]));
+                }
             }
 
             if ($esearch) {
@@ -2067,7 +2153,7 @@
 
                 $result = array();
                 for ($i=0; $i<count($items); $i++) {
-                    // If the SEARCH results in no matches, the server MUST NOT
+                    // If the SEARCH returns no matches, the server MUST NOT
                     // include the item result option in the ESEARCH response
                     if ($ret = $this->tokenizeResponse($response, 2)) {
                         list ($name, $value) = $ret;
@@ -2116,7 +2202,6 @@
      *
      * @return array List of mailboxes or hash of options if $status_opts argument
      *               is non-empty.
-     * @access public
      */
     function listMailboxes($ref, $mailbox, $status_opts=array(), $select_opts=array())
     {
@@ -2132,7 +2217,6 @@
      *
      * @return array List of mailboxes or hash of options if $status_opts argument
      *               is non-empty.
-     * @access public
      */
     function listSubscribed($ref, $mailbox, $status_opts=array())
     {
@@ -2152,7 +2236,6 @@
      *
      * @return array List of mailboxes or hash of options if $status_ops argument
      *               is non-empty.
-     * @access private
      */
     private function _listMailboxes($ref, $mailbox, $subscribed=false,
         $status_opts=array(), $select_opts=array())
@@ -2231,7 +2314,7 @@
         return false;
     }
 
-    function fetchMIMEHeaders($mailbox, $id, $parts, $mime=true)
+    function fetchMIMEHeaders($mailbox, $uid, $parts, $mime=true)
     {
         if (!$this->select($mailbox)) {
             return false;
@@ -2249,7 +2332,7 @@
             $peeks[] = "BODY.PEEK[$part.$type]";
         }
 
-        $request = "$key FETCH $id (" . implode(' ', $peeks) . ')';
+        $request = "$key UID FETCH $uid (" . implode(' ', $peeks) . ')';
 
         // send request
         if (!$this->putLine($request)) {
@@ -2263,7 +2346,7 @@
 
             if (preg_match('/BODY\[([0-9\.]+)\.'.$type.'\]/', $line, $matches)) {
                 $idx = $matches[1];
-                $result[$idx] = preg_replace('/^(\* '.$id.' FETCH \()?\s*BODY\['.$idx.'\.'.$type.'\]\s+/', '', $line);
+                $result[$idx] = preg_replace('/^(\* [0-9]+ FETCH \()?\s*BODY\['.$idx.'\.'.$type.'\]\s+/', '', $line);
                 $result[$idx] = trim($result[$idx], '"');
                 $result[$idx] = rtrim($result[$idx], "\t\r\n\0\x0B");
             }
@@ -2570,33 +2653,6 @@
         return false;
     }
 
-    function fetchStructureString($mailbox, $id, $is_uid=false)
-    {
-        if (!$this->select($mailbox)) {
-            return false;
-        }
-
-        $key = $this->nextTag();
-        $result = false;
-        $command = $key . ($is_uid ? ' UID' : '') ." FETCH $id (BODYSTRUCTURE)";
-
-        if ($this->putLine($command)) {
-            do {
-                $line = $this->readLine(5000);
-                $line = $this->multLine($line, true);
-                if (!preg_match("/^$key /", $line))
-                    $result .= $line;
-            } while (!$this->startsWith($line, $key, true, true));
-
-            $result = trim(substr($result, strpos($result, 'BODYSTRUCTURE')+13, -1));
-        }
-        else {
-            $this->setError(self::ERROR_COMMAND, "Unable to send command: $command");
-        }
-
-        return $result;
-    }
-
     function getQuota()
     {
         /*
@@ -2660,7 +2716,6 @@
      *
      * @return boolean True on success, False on failure
      *
-     * @access public
      * @since 0.5-beta
      */
     function setACL($mailbox, $user, $acl)
@@ -2684,7 +2739,6 @@
      *
      * @return boolean True on success, False on failure
      *
-     * @access public
      * @since 0.5-beta
      */
     function deleteACL($mailbox, $user)
@@ -2702,7 +2756,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return array User-rights array on success, NULL on error
-     * @access public
      * @since 0.5-beta
      */
     function getACL($mailbox)
@@ -2743,7 +2796,6 @@
      * @param string $user    User name
      *
      * @return array List of user rights
-     * @access public
      * @since 0.5-beta
      */
     function listRights($mailbox, $user)
@@ -2775,7 +2827,6 @@
      * @param string $mailbox Mailbox name
      *
      * @return array MYRIGHTS response on success, NULL on error
-     * @access public
      * @since 0.5-beta
      */
     function myRights($mailbox)
@@ -2802,7 +2853,6 @@
      * @param array  $entries Entry-value array (use NULL value as NIL)
      *
      * @return boolean True on success, False on failure
-     * @access public
      * @since 0.5-beta
      */
     function setMetadata($mailbox, $entries)
@@ -2832,7 +2882,6 @@
      *
      * @return boolean True on success, False on failure
      *
-     * @access public
      * @since 0.5-beta
      */
     function deleteMetadata($mailbox, $entries)
@@ -2862,7 +2911,6 @@
      *
      * @return array GETMETADATA result on success, NULL on error
      *
-     * @access public
      * @since 0.5-beta
      */
     function getMetadata($mailbox, $entries, $options=array())
@@ -2954,7 +3002,6 @@
      *                        three elements: entry name, attribute name, value
      *
      * @return boolean True on success, False on failure
-     * @access public
      * @since 0.5-beta
      */
     function setAnnotation($mailbox, $data)
@@ -2986,7 +3033,6 @@
      *
      * @return boolean True on success, False on failure
      *
-     * @access public
      * @since 0.5-beta
      */
     function deleteAnnotation($mailbox, $data)
@@ -3008,7 +3054,6 @@
      *
      * @return array Annotations result on success, NULL on error
      *
-     * @access public
      * @since 0.5-beta
      */
     function getAnnotation($mailbox, $entries, $attribs)
@@ -3093,10 +3138,103 @@
     }
 
     /**
+     * Returns BODYSTRUCTURE for the specified message.
+     *
+     * @param string $mailbox Folder name
+     * @param int    $id      Message sequence number or UID
+     * @param bool   $is_uid  True if $id is an UID
+     *
+     * @return array/bool Body structure array or False on error.
+     * @since 0.6
+     */
+    function getStructure($mailbox, $id, $is_uid = false)
+    {
+        $result = $this->fetch($mailbox, $id, $is_uid, array('BODYSTRUCTURE'));
+        if (is_array($result)) {
+            $result = array_shift($result);
+            return $result->bodystructure;
+        }
+        return false;
+    }
+
+    static function getStructurePartType($structure, $part)
+    {
+	    $part_a = self::getStructurePartArray($structure, $part);
+	    if (!empty($part_a)) {
+		    if (is_array($part_a[0]))
+                return 'multipart';
+		    else if ($part_a[0])
+                return $part_a[0];
+	    }
+
+        return 'other';
+    }
+
+    static function getStructurePartEncoding($structure, $part)
+    {
+	    $part_a = self::getStructurePartArray($structure, $part);
+	    if ($part_a) {
+		    if (!is_array($part_a[0]))
+                return $part_a[5];
+	    }
+
+        return '';
+    }
+
+    static function getStructurePartCharset($structure, $part)
+    {
+	    $part_a = self::getStructurePartArray($structure, $part);
+	    if ($part_a) {
+		    if (is_array($part_a[0]))
+                return '';
+		    else {
+			    if (is_array($part_a[2])) {
+				    $name = '';
+				    while (list($key, $val) = each($part_a[2]))
+                        if (strcasecmp($val, 'charset') == 0)
+                            return $part_a[2][$key+1];
+			    }
+		    }
+	    }
+
+        return '';
+    }
+
+    static function getStructurePartArray($a, $part)
+    {
+	    if (!is_array($a)) {
+            return false;
+        }
+	    if (strpos($part, '.') > 0) {
+		    $original_part = $part;
+		    $pos = strpos($part, '.');
+		    $rest = substr($original_part, $pos+1);
+		    $part = substr($original_part, 0, $pos);
+		    if ((strcasecmp($a[0], 'message') == 0) && (strcasecmp($a[1], 'rfc822') == 0)) {
+			    $a = $a[8];
+		    }
+		    return self::getStructurePartArray($a[$part-1], $rest);
+	    }
+        else if ($part>0) {
+		    if (!is_array($a[0]) && (strcasecmp($a[0], 'message') == 0)
+                && (strcasecmp($a[1], 'rfc822') == 0)) {
+			    $a = $a[8];
+		    }
+		    if (is_array($a[$part-1]))
+                return $a[$part-1];
+		    else
+                return $a;
+	    }
+        else if (($part == 0) || (empty($part))) {
+		    return $a;
+	    }
+    }
+
+
+    /**
      * Creates next command identifier (tag)
      *
      * @return string Command identifier
-     * @access public
      * @since 0.5-beta
      */
     function nextTag()
@@ -3115,7 +3253,6 @@
      * @param int    $options   Execution options
      *
      * @return mixed Response code or list of response code and data
-     * @access public
      * @since 0.5-beta
      */
     function execute($command, $arguments=array(), $options=0)
@@ -3126,7 +3263,9 @@
         $response = $noresp ? null : '';
 
         if (!empty($arguments)) {
-            $query .= ' ' . implode(' ', $arguments);
+            foreach ($arguments as $arg) {
+                $query .= ' ' . self::r_implode($arg);
+            }
         }
 
         // Send command
@@ -3173,7 +3312,6 @@
      * @param int    $num  Number of tokens to return
      *
      * @return mixed Tokens array or string if $num=1
-     * @access public
      * @since 0.5-beta
      */
     static function tokenizeResponse(&$str, $num=0)
@@ -3194,7 +3332,7 @@
                 if (!is_numeric(($bytes = substr($str, 1, $epos - 1)))) {
                     // error
                 }
-                $result[] = substr($str, $epos + 3, $bytes);
+                $result[] = $bytes ? substr($str, $epos + 3, $bytes) : '';
                 // Advance the string
                 $str = substr($str, $epos + 3 + $bytes);
                 break;
@@ -3223,10 +3361,12 @@
 
             // Parenthesized list
             case '(':
+            case '[':
                 $str = substr($str, 1);
                 $result[] = self::tokenizeResponse($str);
                 break;
             case ')':
+            case ']':
                 $str = substr($str, 1);
                 return $result;
                 break;
@@ -3243,8 +3383,8 @@
                     break;
                 }
 
-                // excluded chars: SP, CTL, )
-                if (preg_match('/^([^\x00-\x20\x29\x7F]+)/', $str, $m)) {
+                // excluded chars: SP, CTL, ), [, ]
+                if (preg_match('/^([^\x00-\x20\x29\x5B\x5D\x7F]+)/', $str, $m)) {
                     $result[] = $m[1] == 'NIL' ? NULL : $m[1];
                     $str = substr($str, strlen($m[1]));
                 }
@@ -3253,6 +3393,23 @@
         }
 
         return $num == 1 ? $result[0] : $result;
+    }
+
+    static function r_implode($element)
+    {
+        $string = '';
+
+        if (is_array($element)) {
+            reset($element);
+            while (list($key, $value) = each($element)) {
+                $string .= ' ' . self::r_implode($value);
+            }
+        }
+        else {
+            return $element;
+        }
+
+        return '(' . trim($string) . ')';
     }
 
     private function _xor($string, $string2)
@@ -3348,7 +3505,6 @@
      *
      * @param   boolean $debug      New value for the debugging flag.
      *
-     * @access  public
      * @since   0.5-stable
      */
     function setDebug($debug, $handler = null)
@@ -3362,7 +3518,6 @@
      *
      * @param   string  $message    Debug mesage text.
      *
-     * @access  private
      * @since   0.5-stable
      */
     private function debug($message)
diff --git a/program/include/rcube_message.php b/program/include/rcube_message.php
index 4e25955..2ec386c 100644
--- a/program/include/rcube_message.php
+++ b/program/include/rcube_message.php
@@ -77,7 +77,7 @@
         $this->imap->get_all_headers = true;
 
         $this->uid = $uid;
-        $this->headers = $this->imap->get_headers($uid, NULL, true, true);
+        $this->headers = $this->imap->get_message($uid);
 
         if (!$this->headers)
             return;
@@ -94,9 +94,9 @@
                 '_mbox' => $this->imap->get_mailbox_name(), '_uid' => $uid))
         );
 
-        if ($this->structure = $this->imap->get_structure($uid, $this->headers->body_structure)) {
-            $this->get_mime_numbers($this->structure);
-            $this->parse_structure($this->structure);
+        if (!empty($this->headers->structure)) {
+            $this->get_mime_numbers($this->headers->structure);
+            $this->parse_structure($this->headers->structure);
         }
         else {
             $this->body = $this->imap->get_body($uid);
diff --git a/program/include/rcube_mime_struct.php b/program/include/rcube_mime_struct.php
index c649425..ed28af3 100644
--- a/program/include/rcube_mime_struct.php
+++ b/program/include/rcube_mime_struct.php
@@ -1,77 +1,7 @@
-<?php
 
-
-/*
- +-----------------------------------------------------------------------+
- | program/include/rcube_mime_struct.php                                 |
- |                                                                       |
- | This file is part of the Roundcube Webmail client                     |
- | Copyright (C) 2005-2011, The Roundcube Dev Team                       |
- | Licensed under the GNU GPL                                            |
- |                                                                       |
- | PURPOSE:                                                              |
- |   Provide functions for handling mime messages structure              |
- |                                                                       |
- |   Based on Iloha MIME Library. See http://ilohamail.org/ for details  |
- |                                                                       |
- +-----------------------------------------------------------------------+
- | Author: Aleksander Machniak <alec@alec.pl>                            |
- | Author: Ryo Chijiiwa <Ryo@IlohaMail.org>                              |
- +-----------------------------------------------------------------------+
-
- $Id$
-
-*/
-
-/**
- * Helper class to process IMAP's BODYSTRUCTURE string
- *
- * @package    Mail
- * @author     Aleksander Machniak <alec@alec.pl>
- */
-class rcube_mime_struct
-{
-    private $structure;
-
-
-    function __construct($str=null)
+    function getStructurePartType($structure, $part)
     {
-        if ($str)
-            $this->structure = $this->parseStructure($str);
-    }
-
-    /*
-     * Parses IMAP's BODYSTRUCTURE string into array
-    */
-    function parseStructure($str)
-    {
-        $line = substr($str, 1, strlen($str) - 2);
-        $line = str_replace(')(', ') (', $line);
-
-	    $struct = rcube_imap_generic::tokenizeResponse($line);
-    	if (!is_array($struct[0]) && (strcasecmp($struct[0], 'message') == 0)
-		    && (strcasecmp($struct[1], 'rfc822') == 0)) {
-		    $struct = array($struct);
-	    }
-
-        return $struct;
-    }
-
-    /*
-     * Parses IMAP's BODYSTRUCTURE string into array and loads it into class internal variable
-    */
-    function loadStructure($str)
-    {
-        if (empty($str))
-            return true;
-
-        $this->structure = $this->parseStructure($str);
-        return (!empty($this->structure));
-    }
-
-    function getPartType($part)
-    {
-	    $part_a = $this->getPartArray($this->structure, $part);
+	    $part_a = self::getPartArray($structure, $part);
 	    if (!empty($part_a)) {
 		    if (is_array($part_a[0]))
                 return 'multipart';
@@ -82,9 +12,9 @@
         return 'other';
     }
 
-    function getPartEncoding($part)
+    function getStructurePartEncoding($structure, $part)
     {
-	    $part_a = $this->getPartArray($this->structure, $part);
+	    $part_a = self::getPartArray($structure, $part);
 	    if ($part_a) {
 		    if (!is_array($part_a[0]))
                 return $part_a[5];
@@ -93,9 +23,9 @@
         return '';
     }
 
-    function getPartCharset($part)
+    function getStructurePartCharset($structure, $part)
     {
-	    $part_a = $this->getPartArray($this->structure, $part);
+	    $part_a = self::getPartArray($structure, $part);
 	    if ($part_a) {
 		    if (is_array($part_a[0]))
                 return '';
@@ -112,7 +42,7 @@
         return '';
     }
 
-    function getPartArray($a, $part)
+    function getStructurePartArray($a, $part)
     {
 	    if (!is_array($a)) {
             return false;
@@ -137,9 +67,7 @@
 		    else
                 return $a;
 	    }
-        else if (($part==0) || (empty($part))) {
+        else if (($part == 0) || (empty($part))) {
 		    return $a;
 	    }
     }
-
-}
diff --git a/program/steps/mail/func.inc b/program/steps/mail/func.inc
index ae0d3a5..ab4b290 100644
--- a/program/steps/mail/func.inc
+++ b/program/steps/mail/func.inc
@@ -1454,7 +1454,7 @@
   if (!is_object($message) || !is_a($message, rcube_message))
     $message = new rcube_message($message);
 
-  if ($message->headers->mdn_to && !$message->headers->mdn_sent &&
+  if ($message->headers->mdn_to && !$message->headers->mdnsent &&
     ($IMAP->check_permflag('MDNSENT') || $IMAP->check_permflag('*')))
   {
     $identity = $RCMAIL->user->get_identity();
diff --git a/program/steps/mail/show.inc b/program/steps/mail/show.inc
index 1472a9e..ba172c7 100644
--- a/program/steps/mail/show.inc
+++ b/program/steps/mail/show.inc
@@ -77,7 +77,7 @@
 
   // check for unset disposition notification
   if ($MESSAGE->headers->mdn_to &&
-      !$MESSAGE->headers->mdn_sent && !$MESSAGE->headers->seen &&
+      !$MESSAGE->headers->mdnsent && !$MESSAGE->headers->seen &&
       ($IMAP->check_permflag('MDNSENT') || $IMAP->check_permflag('*')) &&
       $mbox_name != $CONFIG['drafts_mbox'] &&
       $mbox_name != $CONFIG['sent_mbox'])

--
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