A show stopper for me is that I can't set up my Zimbra client to leave messages on the (POP3) server for a period of time as I can do with other email clients. I get the bogus error: "The POP3 server does not support leaving messages on server (UIDL support required)". I need to do this because we access our pop account from multiple computers. If I try to use Zimbra, it will grab all the email from the server immediately and my wife's computer won't see it. Until this is fixed, Zimbra is useless to me.