Possible Duplicate:
Exchange server replacement that runs on Linux

I'm setting up a Debian server, and one of the things I need on it is an MTA. I don't want to use something like Exim or Postfix because I want something that ties in SMTP, POP3, and IMAP all in one (a la Microsoft Exchange). Most MTAs also seem to be hellishly difficult to configure. Try and read the Exim documentation; you could do a university degree on it (I'm not kidding).

When you can get an HTTP server like Cherokee which is easy to configure and has a nice web interface, do MTAs or groupware solutions need to be that hard? I'm aware that some people think "the Unix way" is to have lots of different interacting pieces of software (like maybe an SMTP MTA, POP3 service, webmail service, and overarching manager to tie them all together), but I think this is a situation where that just makes things a lot harder to deal with and one large software suite fits in much more nicely. So, I'm looking for good open source software suites that will run on Debian that:

• Combine (at least) SMTP, POP3, and IMAP
• Are easy(ish) to configure
• Have a nice configuration web interface or GUI
• Are not defunct projects

I don't mind if it's groupware and offers calendaring too, but I would only be using the e-mail functionality for now. Another nice-to-have would be built-in webmail (if we're combining a bunch of functionality, why not?) Note however that I do NOT need Outlook support. I am not really looking for an "Exchange replacement drop-in".

The suites I've found so far that seem to match the above criteria (and have appropriate licenses) are Citadel, Kolab, and Zimbra. I'd appreciate anyone who has experience with any of these giving me the pros and cons of them, such as how easy they are to configure and what their performance is like. I'd also appreciate any other suggestions for solutions that fulfil my criteria that I may have missed out.