The command pipelining fix is pretty interesting. Wonder how much it improves performance, especially when deleting lots of messages from a large mailbox.
v1.1.15 2009-05-17 Timo Sirainen email@example.com
+ IMAP: When multiple commands are pipelined, try harder to combine their mailbox syncing together. For example with Maildir pipelining STORE 1:* +FLAGS \Deleted and EXPUNGE commands the files won't be unnecessarily rename()d before being unlink()ed. - IMAP: SEARCH command was slower than necessary in a large mailbox. - deliver: When forwarding messages, if -f parameter was given, it should have been used as the Return-Path. - Maildir saving: Fixed race condition bugs in uidlist handling, causing files to be given new UIDs sometimes. - mbox: Don't crash when expunging all messages and file doesn't end with [CR]LF. - expire-tool: Use mail_uid and mail_gid settings if userdb doesn't return uid/gid. - Berkeley DB dict: Transaction rollbacking was implemented wrong. - zlib plugin: Some email / FETCH command combinations could have disconnected the client or sent compressed garbage.