interface/web/admin/form/server_config.tform.php
@@ -381,6 +381,10 @@ 'mailbox_virtual_uidgid_maps' => array( 'datatype' => 'VARCHAR', 'formtype' => 'CHECKBOX', 'validators' => array (0 => array ( 'type' => 'CUSTOM', 'class' => 'validate_server_mail_config', 'function' => 'mailbox_virtual_uidgid_maps'), ), 'default' => 'n', 'value' => array(0 => 'n', 1 => 'y') ),