Hi..we waiting for Zimbra to release some stable version for production so we can really do some stress and scalibity tests.
if this takes the the load and works for us we plan to move 100% for our email stuff to zimbra.
we were anyway working on Postfix + SA + mySQL + clamAVS and others to come up with a solution but lack of Scalable Web Mail or Web access is a big deal and all PERL or PHP based webmail system are resource hogs and loop a lot for large mailboxes (try 2000 email in inbox with any of these)..
with Imail we have 15000 - 20000 email in inbox and it works like a charm..but it cost $$$
..lots of them ...lol
we plan start on our Migration tools as soon as we 100% sure Zimbra is the one we will be using..so far it looks good .
Raj S Vrach
i2k2systems.com