I've just upgraded from a 3.1.3 setup to 4.1 which turned out to be a fairly painless job. What confuses me no end is that I cannot get the imapproxy service to start, although imap(s) is clearly still working:
$ /opt/zimbra/bin/zmcontrol start
imap4 is not running
imap4s is not running
pop3 is not running
pop3s is not running
And yes, I can retrieve/save messages via imaps just fine...
# lsof -i :993
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
java 26559 zimbra 17u IPv6 120258 TCP *:imaps (LISTEN)
java 26559 zimbra 35u IPv6 120371 TCP gug.nodomain.com:imaps->tuna68.nodomain.com:47421 (ESTABLISHED)
java 26559 zimbra 40u IPv6 121521 TCP gug.nodomain.com:imaps->tuna68.nodomain.com:57138 (ESTABLISHED)
Honestly I don't know exactly what the significange of imapproxy is and I can obviously live with the situation as everything is working. However, I'd rather fix it now lest it jumps up and bites me somewhere down the road. I checked the logs in /opt/zimbra/log and also the forums, but couldn't find anything specific about this issue.
It might have something to do with this beeing a fairly 'old' setup that was incrementally upgraded from somewhere around 3.0 beta through the various 3.0 and 3.1 releases. Maybe something fell through the cracks somewhere.