1)   Winmail Mail Server 4.3
Winmail Server is an enterprise class mail server software system offering a robust feature set, including extensive security measures. Winmail Server supports SMTP, POP3, IMAP, Webmail, LDAP, multiple domains, SMTP authentication, spam protection

 2)   IA Corporate Email Server 6.1
The Internet Anywhere Corporate Email Server is a high performance, multi-threaded email server which supports IMAP, POP3 and SMTP. It provides everything you need to run a secure and dependable email system.

 3)   NoticeWare Email Server 4.3
The NoticeWare Email Server is a high performance, multi-threaded email server for Windows NT4/2000/2003/XP which supports IMAP, POP3 and SMTP. It provides everything you need to run a secure and dependable email system.