On Jan 13, 2009, at 10:45 AM, Michael Durket wrote:

I've been testing Dovecot for a while now and am preparing to
replace our outdated IMAP system with it. The current system serves about 300 email users who
run a mixture of clients (Eudora, Apple Mail, Thunderbird and Outlook). Can any of
the many experts on this list answer a few questions:

1. What's the latest stable release of Dovecot I should be
   running on this new system (Dovecot will be running on a RedHat Linux AS 4 64 bit
   system with plenty of memory and CPU). I've been running 1.13 on my test system but I see
   that 1.18 just came out (although I don't know if I should switch to it
   immediately.

I recommend 1.1.8. Especially if you're planning on using mbox format,
since it fixes several bugs related to it.

2. What configuration file options (if any) should I turn on to
   best handle the range of email clients listed above?

Look at the imap_client_workarounds setting and enable the ones you
need.

3. Are there any "sizing" options I need to worry about setting
   for the number of email users I have (I suspect that 300 users is considered
   a rather small mail system but I want to minimize its resource usage as
   much as possible while still giving decent performance from Dovecot).

Not really. The default options should be fine for that. Anyway see http://wiki.dovecot.org/PerformanceTuning

And, just out of curiosity, I'm looking into the idea of switching
users from mbox format over to Maildir format on this system (it will use all locally- connected disks and have no NFS mounts). Does the Dovecot automatic migration program to migrate
from mbox to Maildir work well or are there "gotchas"?

It doesn't preserve message UIDs, which causes clients to redownload
them. This isn't such a big deal with IMAP, but if you have any POP3
users that could be a problem (although you should make sure
pop3_uidl_format is correct in any case).

I'd anyway recommend using one of the scripts that preserves UIDs,
just in case. http://dovecot.org/list/dovecot/2008-March/029736.html
apparently should work.

Also you should configure Dovecot to use '/' as the namespace
separator for maildir too. Some clients don't like it when the
separator changes unexpectedly. Also the '/' is more "standard"
anyway. You might also want http://wiki.dovecot.org/Plugins/Listescape
to allow using '.' characters in mailbox names, which you might
already have.