Phil Howard <ttiphil@gmail.com>:
And I fully accept that as a sufficient reason to make a choice. I made the choice of Dovecot, having zero experience with it, because of my experience with Courier. Sadly, making such a choice with zero experience and zero knowledge of either options is the really hard one to make.
Ah, wrt. to IMAP servers I at least have the experience of three different servers: UoW imapd, Cyrus imapd and now dovecot.
Based on that selection: dovecot is by _far_ the simplest one to get started with, and by far the most stable and scalable.
The second time a cyrus upgrade trashed my read marks I started looking for a replacement, and a quick google search found me dovecot.
I took some time figuring out what method I should use to transfer the mailboxes, and eventually settled on imapsync. I set up dovecot on a different machine than the one cyrus was running on, used imapsync to pull the mailboxes over, and then shut down cyrus on the first machine, installed dovecot, rsync'd the mailboxes back, and was up and running with the new dovecot.
As a bonus I could go back to use procmail for mail filtering. It's ugly... but I know it...