I am experiencing the exact same problem here.
My version is:
Release 4.5.3_GA_733.FC4_20070228105543 FC4 FOSS edition
My Zimbra has been working PERFECTLY (let me stress this) for months now, with absolutely no problems. However in the last few days, the mailbox service stops. There is no nasty stack dumps in the catalina.log or even the mailbox log files. It just stops.
Nothing has changed on the system. (yeah sure they all say that)
But I can assure you nothing has changed, since at this precise moment, everyone is on their holidays, and the server is physically not being touched!
The only thing that has changed, is the load on the server in terms of the web mail client. Since we are using that to check our email (some using the basic interface) that is the only thing that has changed in terms of behavior.
That said, we are talking all of 3 users! And the time the mailbox stops logging is at 0400 in the morning, the time when everyone is asleep.
So the question really is ... WTF!
