Launching Next has discovered 2 mail server startups.
Zimbra offers Open Source email server software and shared calendar for Linux and the Mac.
Zimbra provides open source email and calendar groupware software, Zimbra is a popular choice for Linux and Mac OS X email servers and supports SaaS deployment, appliances and virtualization platforms.
Mail Server Software, Help Desk Software, & Web Analytics
SmarterTools develops mail server software, help desk software, and web analytics for small businesses, web hosts, and ISPs.