Last night we upgraded our M2 install to M3. We currently run a 2 machine setup of zimbra. Machine A is a dedicated mail store, imap, pop, and outgoing smtp. Our second machine is a dedicated spam/virus filter. We have roughly 1500 accounts on the system. After a horrible experience with an M1 to M2 (luckily there was only about 15 accounts on the system at that time) we were stressing and very hesitant to upgrade to M3. This upgrade however went much much smoother. Few minor issues here and there, primarly with zimbra not being fully killed by the scripts during the install which we had to kill by hand but other then that the transition went smoothly. We had both machines upgraded in about an hour, so for that, much thanks to the development team for making the upgrade so smoothly.

Few minor bugs that i've noticed.
First and formost in the admin console. While creating a new user you have the drop down box to select the domain that user belongs to. Well i've tried it on two different computers (granted same O.S. OS X 10.4.4 firefox (no safari support yet) in both cases the drop down box will not drop down. I've been able to add users via CML so not a huge deal. I wasn't able to try on IE for lack of a windows machine.

Other issue is when logged into admin interface i select an account and click View Mail button. This shows the page not found in firefox. I'm almost positive that this is a Http vs https issue so i'll play with that during non business hours (i hate to "tinker" in the middle of the customer's work day). Right now its trying to access it via https however webmail users use straight http.

Again thank for the smooth transition during the upgrade.