FS#3574 - Improve corrupt maildir removal function

Till Brehm

2014-07-27 a6a997ee36ac59d0f079ac26da87412f5dfdef2c

1
ALTER TABLE  `sys_session` CHANGE  `session_id`  `session_id` VARCHAR( 64 ) CHARACTER SET latin1 COLLATE latin1_swedish_ci NOT NULL;