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.
ClearVoice - ClearVoice is a content marketing platform and service solution.
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).
SnapApp - SnapApp is an interactive content creation platform.
mailcow - An open source mailserver suite.
Percolate - Content Marketing Redefined. Percolate is the first end-to-end technology for content marketing.