+1 for Zimbra as well, is a very nice Exchange replacement! Having said that, Zimbra was just acquired recently (yes, AGAIN) and this fact makes me nervous, not sure whether to despair or rejoice.[1]

Mailpipe, if it ever happens, should help a lot getting some of that mail from the claws of Gmail and the likes. They can have my money.

[1] - https://blog.zimbra.com/blog/archives/2013/07/telligent-acqu...