This is actually a spin-off from my previous thread, as with help from Ubuntu and Phoenix I narrowed down the source of the problem.
Release 4.5.11_GA_1751.FC5_20080128130403 FC5 FOSS edition running on single server.
Ran for a couple of years without many incidents until I tried to connect from Outlook client with IMAP. Discovered that IMAP service was disabled (in Admin Console/Server Settings & Global Settings).
Soon as I enabled it and restarted the server, mailbox stopped. Due to my own inexperience it took a while and the assistance of Ubuntu & Phoenix to get it going again.
Now the problem is repeatable and correctable: enabling IMAP stops tomcat running, which in turn stops the mailbox. Running zmperditionctl stop and then tomcat start, gets things going again.
So question is why? Obviously starting IMAP on port 143 is conflicting with tomcat somehow, which is probably why the guy that installed ZCS for us left it disabled instead of finding the cause (thanks....), but I'd really like to resolve it and begin using IMAP again.
Would it be as simple as configuring a different port for IMAP in perdition?
Any suggestions most welcome.