OBM - OBM is a free messaging and collaboration platform useful for just a couple to many thousands of users with strong support for mobile devices.
Dovecot - Dovecot is an open source IMAP and POP3 email server for Linux/UNIX-like systems, written with...
Microsoft Exchange Server - Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft.
Cyrus IMAP - The Cyrus IMAP server differs from other IMAP server implementations in that it is generally...
Zimbra - Zimbra is trusted by over 500 million users to increase productivity with a complete set of collaboration tools while maintaining total control over security and privacy.
DBMail - DBMail is a fast, scalable IMAP4 and POP3 server that stores all email and users in a Postgresql...