Open Source Microsoft Exchange Server Alternatives
The best open source alternative to Microsoft Exchange Server is Kopano. If that doesn't suit you, our users have ranked more than 25 alternatives to Microsoft Exchange Server and 17 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Microsoft Exchange Server are hMail Server, mailcow: dockerized, Zentyal and Zimbra Collaboration Suite.
Microsoft Exchange Server alternatives are mainly Mail Servers but may also be WebMail Providers or Calendar Apps. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of Microsoft Exchange Server.- Paid • Proprietary
- Windows
- Online
- Freemium • Open Source
- Mac
- Windows
- Linux
- Online
- Android
- iPhone
- Android Tablet
- Windows Phone
- iPad
- Self-Hosted
- Microsoft Office Outlook
- S/MIME
- Software as a Service (SaaS)
Kopano puts an email, video meetings, calendaring, and file sharing solution within one single interface.
Kopano vs Microsoft Exchange Server opinions
hn1Kopano has scalable backend and can do full MAPI server and clientside. The Webapp and Deskapp has intuitive and modern UI/UX.
bobspScalable, open source with a great UX and it has all the features I need
marcskiStable and cheap backend, flexible frontend support, open source, in full control of your data
OpenSource, better to maintain, "not Microsoft"
I tried a lot of MS alternatives, OX, Zimbra, Zentyal, but what fits most with Outlook Sync was the new Kopano, it's more flexible. You can use the web app or desktop app too.
- Free • Open Source
- Windows
hMailServer is a free e-mail server for Microsoft Windows. Its used by Internet service providers, companies, governments, schools and enthusiasts in all parts of the world.
- Free • Open Source
- Linux
- Self-Hosted
mailcow is a mail server suite based on Dovecot, Postfix, SOGo, Rspamd and other open source software, that provides a modern Web UI for administration.
- Paid • Open Source
- Linux
Zentyal is a native Microsoft Active Directory implementation on Linux incorporating all the network services required in a small and medium business environment: Directory & Domain Server, Mail Server, Gateway and Infrastructure Server.
Zentyal vs Microsoft Exchange Server opinions
No Exchange alternative and no support for MS Outlook Client
While the comments below suggest that this is AD, not exchange replacement. It was supposed to ship with SoGo / openchange as a managed add-on. You also strangely enough can't have exchange without AD. but guests do keep on posting. Exchange is just an Add-On to AD. (It extends the schema).
They do not share any common functionality. Zentyal is an Active Directory substitute, Microsoft Exchange is a groupware E-Mail (enterprise grade) server.
Not an Exchange alternative at all. Does basic AD but that is about it. It is more of a gateway server.
- Freemium • Open Source
- Linux
- Online
- Self-Hosted
Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more. With the most innovative web application available today, Zimbra boosts the productivity of users on any desktop and dramatically reduces TCO compared to legacy platform vendors.
- Freemium • Open Source
- Linux
- Online
- Self-Hosted
Kolab is entirely Free and Open Source Software (a.k.a. FOSS), and uses Open Standards. We’ll get to why this is important to us, and hope that it is important to you thereafter.
No screenshots yet- Freemium • Open Source
- Linux
- Online
- Thunderbird
- Cloudron
SOGo is groupware server with a focus on scalability and open standards.
- Paid • Open Source
- Online
- Software as a Service (SaaS)
- DAVdroid
Kolab Now provides a suite of intuitive apps in a user friendly environment to make your day to day online comms easier, smarter and most importantly; secure.
Kolab Now vs Microsoft Exchange Server opinions
With Microsoft no longer supporting our existing setup, this was a great alternative.
A fully fledged, free email server solution, an open source project (GPL v2).
OpenChange aims to provide a portable Open Source implementation of Microsoft Exchange Server and Exchange protocols.
No screenshots yet