WorkgroupMail Mail Server
Full featured mail server that you can install in less than 1 minute.
www.workgroupmail.com

IMAP4 Server
Advanced Windows Mail Server. SMTP, POP3, IMAP4 and WebMail.
www.abilitymailserver.com

eXchange POP3
Downloads email from POP3 accounts and delivers it to Exchange users.
www.exchangepop3.com

C++ MIME Tools
Libraries for high speed message parsing and email tools!
www.hunnysoft.com