[Dovecot] mbox vs maildir

[Tim Tsai]

>>> Can Dovecot handle mbox for some users and maildir for others? I'd 
>>> like to try a conversion for one user... I'll probably create a new
>>> user, then have procmail copy (via ! action code) all mail for one
>>> user to that new user.
>>>       

I recently inherited a sendmail + UW IMAP installation (where hundred 
megabytes mbox files were becoming issues) and have since migrated to 
Postfix + Dovecot and have been very pleased.  During the migration to 
the new server, I set up the old UW IMAP/POP3 on 127.0.0.1 and Perdition 
proxies on the original IP address.   From Perdition you can specify 
which destination server to use via regex so it was easy to transition 
on a per user (or domain or anything else that you can specify via 
regex) basis.  As a matter of fact we migrated the users over a one 
month period and had zero issues.  The final touch was changing the DNS 
to the new server.  Most users did not even know about the change and 
gave us plenty of opportunities for live testing.  The only thing to 
watch out for is that Perdition doesn't know what capabilities to 
advertise for IMAP (especially if the two servers are very different) so 
you have to use the least common eliminator initially.

If getting a new server isn't an option, Xen and VPS environments have 
made provisioning a new server very cheap nowadays...

Tim