hMailServer is a free, open source mail server for Windows. It has support for SMTP, POP3, IMAP, virtual domains, anti virus scanning, distribution lists and much more. It comes with a great COM library that easily can be used for integration. Data is stored in a database server, MySQL or MS SQL, depending on your choice.
Features:
POP3, SMTP, IMAP
Virtual domains
Built-in backup
Scripting
External accounts
Rules
Multilingual
AntiVirus
Spam protection
Routing
MX backup
Mirroring
Multihoming
SQL-support
What's New in version 5.3.4 Beta:
Stability fixes. In certain scenarios, hMailServer could stop processing incoming requests.
FreewareFiles tested hMailServer 5.3.4 Beta on 2010-12-13 using leading
antivirus scanners and found it 100% Clean. It does not contain any form
of malware, spyware, viruses, trojans, etc. We will re-test each updated
version and remove the award as well as the program if found infected.
User Reviews
"Not beta anymore!"
Reviewer: -jonathanbrickman0000
Review Date: 2006-11-24
Average Rating (11 Votes ) 4.82
Pros: None
Cons: None
Other Thoughts: It's now stable, version 4.3 Build 248, and it is excellent. Via localhost, it is serving IMAP folders to Thunderbird faster than Thunderbird is serving its own native format!