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.
uberflip - Organize and Centralize ALL of your Content in minutes
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).
Paperflite - Paperflite is a prospect engagement platform to enable business development reps to see what sells.
mailcow - An open source mailserver suite.
SnapApp - SnapApp is an interactive content creation platform.