Looking for good Open Source email server
For my personal domain I use hMailserver on Windows plus RoundCube on a Linux box for webmail. I can't see any reason RoundCube can't be run on Windows as well, if that's what you prefer.
hMailserver isn't Open Source but it is free. It's simplicity itself to install and configure. It provides SMTP, POP3 and IMAP. It includes built-in spam filtering, although I don't use that and therefore can't tell you how effective it is.
I asked a similar question on Hacker News.
Open-source components (free):
- Postfix for SMTP
- Exim for SMTP
- Lamson for SMTP
- Dovecot for POP3/IMAP
- Courier for POP3/IMAP
- RoundCube for webmail
Self-hosted solutions (full version is not free):
- Atmail - (webmail, POP3/IMAP, SMTP)
- Zimbra - another complete solution
3rd-party-hosted solutions (full version is not free):
- Rackspace email hosting
- Google Apps email hosting
Take a look at Zimbra Collaboration Suite. They have FOSS (Open Source) and Network edition. Great AJAX web client interface. Overall great complete e-mail server.
I'm not aware of many open source email server projects on Windows. There's the free hMailServer, but that seems a little spartan. Since you mentioned that you weren't afraid to pay for something, I'll mention a few closed-source offerings that rival Exchange in functionality and blow it away for price:
- I like the looks of Kerio MailServer, but it's not open-source.
- There's also IPSwitch's iMailServer, but again it's not open-source.
For Linux, you've got quite an array:
- OpenXChange has a community edition that's free for non-commercial use.
- There's the old and faithful Citadel project.
- There's also the often overlooked Zarafa that has a hobbled community edition.
- There was the promising Bongo Project that forked from Hula, but it's alpha and seems abandoned.