I stumbled upon Zimbra a handful of months ago while trying to find a collaboration suite. There were a few choices out there but none as easy to install in concert with as feature rich as Zimbra. Since that time, I have pushed Zimbra on anyone I know or could be interested. I have successfully installed on various linux distros now and setup servers for other people. I've even managed to convert a few exchange users as well.
This product is fantastic and I will continue to push it as much as I can. Thanks for all the great help I've received from the Zimbra staff as well.