Microsoft Exchange Server - Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft.
pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
hMail Server - hMailServer is a free e-mail server for Microsoft Windows.
Zentyal - Linux directory, domain, mail, gateway and infrastructure server for SMBs.
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.
NethServer - NethServer is an operating system for Linux enthusiasts, designed for small offices and medium...