Why is IMAP protocol so difficult to optimize for, and how do Dovecot's index and cache files help? dbox: Dovecot's new high performance mailbox format. Different ways of implementing HA clusters with Dovecot for large installations.
Timo Sirainen has been developing Dovecot POP3/IMAP server for the last seven years. Initially it started as a hobby, but the last few years several different companies have been paying him for Dovecot development. Since January 2009 Timo moved to US and has been working full time for Rackspace Hosting, which is using Dovecot to serve over a million mailboxes.