[Dovecot] imap-login zombies

[Robin Breathe]

Running dovecot-0.99.13 on Solaris9/Sparc with ~25k users, we are having 
regularly recurring problems with large numbers imap-login/pop3-login 
drones, cycling on poll().

Over the course of 1-2 days, the number of such processes slowly rises 
to >1000, exhausts resources, and necessitates that dovecot be restarted 
(having killed all current active and zombie child processes).

Nothing of interest seems to be logged with the possible exception of a 
reasonably high number of aborted logins (~10/hour).

Can anyone offer any guidance as to how to track down this bug and help 
get it resolved? Any help would be much appreciated, as we would very 
much like to see this resolved in the 0.99 branch.

Regards,
Robin