Here are the words of happy Dovecot Users.
Marc Perkel - Junk Email Filter dot com
I use Dovecot on my server at [http://www.ctyme.com/hosting Computer Tyme Hosting] and for my email hosting at [http://www.junkemailfilter.com Junk Email Filter dot com]. I am an old timer with Linux going back to 1996. I migrated forward from the old days when we are all stuck with Sendmail and WU-IMAP. I had been looking for a new IMAP server for quite a while but needed something that I could migrate several hundred active domains to without a lot of down time and complications.
As you know, working on an email system is like operating on a live patient. The email never stops coming in and users never stop reading it. If you shut down the screaming starts and when you come back up you need to be fully functional or people are screaming.
WU-IMAP doesn't really support and kind of meaningful configuration file and the author has some personality issues that makes development slow. WU-IMAP isn't a community with a future. I was also using a patched version of WU-IMAP called VIMAP and that was practically abandoned. It still worked well but if it ever got hacked or I upgraded something that broke it I would have been in a bad situation.
Then there's the MBOX vs MAILDIR wars that are enough to drive a person nuts. I was looking not only for a good IMAP package, but an author and a community that is more reality based than making religious wars out of trivial issues. MBOX and MAILDIR have their advantages and disadvantages. The BIG advantage of MBOX for me was that I was already using it and needed something compatible.
Timo is the kind of person I was looking for. His philosophy is to make things work and I appreciate that Dovecot is MBOX and MAILDIR compatible. I'm still using MBOX and MAILDIR is probably better, and I'll likely migrate to it someday. But for now I wasn't ready to make all those changes at once. Timo was very responsive in adding the features I needed to be Linuxconf compatible so that I could port all my domains without having to change the way I store user and password configurations. The transition was very smooth and the software just works.
Personality is a big factor to me in who I like to work with. The Dovecot culture is very progressive and they tend to think more outside the box. I am particularly impressed with the readability of the configuration files. It is very similar in nature to Exim in that it works well, is readable, well designed, and no huge egos that get in the way of innovation. I'm inspired enough that I've spent several hours in this wiki helping with documentation, including starting this page.