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).
G Suite
Google’s encompassing suite of cloud-based business apps.
GMX
GMX Mail is a German-based free webmail service provided by GMX (Global Mail Exchange).
Horde
Horde Groupware is a free, enterprise ready, browser based collaboration suite.
Kolab Community
Kolab Groupware is a secure, scalable, reliable, flexible, full-featured collaboration suite.
Kopano
Sharing & communication software for business
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.
OX Open-Xchange
Open-Xchange Server 6 is the most advanced Linux based Groupware solution f.
Roundcube
Web-based IMAP email client
SOGo
SOGo is groupware server with a focus on scalability and open standards.
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.
Zoho One
Zoho is an all-in-one online office suite.
iMail
Fast, safe, heavy mail solution.
iRedMail
A fully fledged, free email server solution, an open source project (GPL v2).