CentOS 5 Server :: Lookin' For Some Email Recommendations?

I'm setting up an email server for a small office and need a few specific features. I was hoping that someone might give me a few recommendations to meet the following criteria:

IMAP support anti-spam some sort of webmail client - doesn't have to be fancy, but it needs a search function graphical administration panel The last one is so that other people in the office, who aren't necessarily familiar with linux, can do some basic administration. Adding mail boxes, etc.

I've seen the guide for Postfix/Dovecot. That's great but doesn't cover everything that I need. I've also seen Zimbra, which... Well I don't know, that may work, but the open source version has some features removed and that makes me leery. Have people had good experiences with open-source Zimbra? Is it sufficiently feature-complete?

Edit: Well, looks like I just needed to do a little more searching. This seems to cover most everything:[URL]... I'd still like to hear what people have to say about Zimbra though.