On Mon, 17 Dec 2012, Chris Ross wrote:

I've been using UW-IMAPd for neigh on forever (at least since 2001). But, as it's basically stalled, and I'm about to update the hardware that is my mail server, I thought it was time to review existing open-source IMAP servers. Dovecot is the top three in my looking.

I converted a few years ago and never looked back.

So, am I right that dovecot supports only the "one big full file" mbox format, and the maildir format? And if so, is it known to allow multiple simultaneous IMAP clients to access and monitor and/or modify the same folder simultaneously?

I still run using mbox, and have not had a problem with corruption, however, this is probably owing to our modest IMAP demand and careful coordination of file locks among all the different MUAs. You're better off with Maildir and other formats, that are better designed for simultaneous access. There are other good reasons to switch formats.

Dovecot also supports its own mdbox/sdbox for high performance: its a hybrid that tries to incorporate the best of both words.

More info

http://wiki2.dovecot.org/MailboxFormat

After those questions, it's just a "what do you think the pros and cons of each are?"

I can't speak to the other software you are looking at, but two factors I found to be particularly good:

- flexibility: you can get almost every oddball setup to work.
	Migration from uw-imapd is fairly easy, but then again,
	uw-imapd didn't have a lot of knobs to turn.  Plugins
	are available that extends its functionality.

- support: this mailing list is great, and Timo is an absolute
	wizard in getting bugs fixed.  (Note: I am shamelessly
	buttering him up so that he fixes the outstanding bug
	I reported!)

Joseph Tam <jtam.home@gmail.com>