I plan to be setting up a mail server soon, and I'd like to stay open source. The two choices which look most promising to me so far, are Apache James, and Courier. Webmail is pretty important for me, so every team member doesn't have to install IMAP programs if they don't want to. Also for public computers. It appears that Courier comes with it's own web-mail, but Apache James does not. However, Huba can be added to Apache James (which is what I'd do if the final consensus was on it).
I will be using IMAP (not POP3), and of course SMTP. Initially it will be 10-20 e-mail accounts, but I don't see why it wouldn't expand to 100 or so in a couple months. I've played with exchange servers before, so I'm not clueless when it comes to mail servers. I'm just not sure how much different an open source mail server would be (besides not containing a reminder that it's an MS product on each item)
Since I am not planning on installing a GUI on the mail server, any kind of graphical admin console that runs locally will not work. Do either of those (or any open source mail servers) contain an HTTP based console? Manual editing isn't too much of a problem, I'm just thinking in terms of convenience, when I want to add a user. I'd rather go to a web console within my network than SSH in to the server, find the specific config/user files, add a new one, save, restart service, or anything of the likes.
Again, if neither of those are particularly good, feel free to recommend your favorite

I'm trying to keep everything open source, though.
P.S. - Spam filtering isn't a major concern, as I plan on setting up an Astaro firewall before I begin issuing e-mail accounts. Although, it can still be somewhat of a concern. Don't completely trust Astaro's spam filter lol.