OpenChange
OpenChange aims to provide a portable Open Source implementation of Microsoft Exchange Server and…
17 Alternatives To OpenChange
Citadel
Is a collaboration suite (messaging and groupware).
Kolab Community
Kolab Groupware is a secure, scalable, reliable, flexible, full-featured collaboration suite.
MDaemon Messaging Server
Low cost, easy to use Email Server software for virtual, on-premise, or hosted deployments for…
Microsoft Exchange Server
Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft.
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.
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.
Zimbra Collaboration Suite
Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more.