I have been seeing the same thing for some time. Seems not client specific, I see it with Evolution, Thunderbird, and Netscape 7.2 mail clients.
I thought it was our firewall but users behind the firewall on the same subnet as the dovecot server have the same problem.
Still working on the migration to Dovecot 1, rc5 but have been seeing this in RH stock rpm dovecot on FC3 and CentOS 4.3.




> But I'd like to know what exactly does "stale processes" mean: Do you
> use SSL and they're all SSL connections?

 
Mine are not SSL. I get as many as 800 IMAP processes (on about 1000 users), this dies down overnight, when no one is checking their mail. 

 

> Are they eating any CPU at all?
 
Nope.




> How long are
> they stuck, or don't they ever die?


They will die ovenight, as no one checks mail after 5 PM. I set a process limit at about 1800 just to be safe. 

 

> How exactly do you know they are stale?

Because the clients have been closed and the user owning the process
does not have any mail applications open.

> Are you sure there aren't any
> clients that still have active connections to it?

Pretty sure - of course it could be the client shutting down uncleanly.
  Mostly 1.5.0.x of Thunderbird and squirrelmail-1.4.6-5.fc5 with an
occasional pine user.




Same here. If I check my mail w/Evolution (and get no new mail) this process stays around for hours.


Sometimes the excessive processes do seem to cause problems (user cannot pop/imap mail, connections auth but hang.
I stop dovecot and wack imap will killall several times, then restart dovecot. This fixes the user problems but within a few mins I have 300-400 imap processes, this grows over the day to about 800-900.



--
James H. Edwards
Network Systems Administrator
Judicial Information Division
jedwards@nmcourts.com