I'm using the Network Edition trial of 4.5.5, and have been pretty happy with it. One issue that I've run into, though, is that when I delete a message from my inbox from either the web interface or an IMAP client, it stays in my inbox on my HTC 8125. I'm making an exchange connection with over the air push. Is there any way to get it to delete messages from the phone's inbox w/o doing it manually in two places? I've got 35 messages in my Zimbra inbox, but 128 in my phone's inbox...
This is a side-effect of weirdnesses in the IMAP protocol. Go into your IMAP client and "expunge" or "compact" your Inbox and everything should propagate to your phone.