I realize this will probably make most Zimbra admins mad, but I think Exchange is a better and a more stable email server. We've been running Zimbra for over a year and we've had nothing but trouble with it. I R&D'd Zimbra when we were considering it and made my suggestion to go with Exchange. However, management decided to go the open source route, and since then, HA has never worked, Zimbra chokes often, the ZCS Connector also chokes often, and the webmail is slow and lacks a lot of functionality (but is a good looking webmail compared to some). Now that MS will own Zimbra, I think Zimbra will only get worse. And before I get an earful, I didn't build our Zimbra servers... I just manage the flow of emails and the users.
