Back in 2013, Microsoft® discontinued their Small Business Server. Since then, there’s been a mad dash by small businesses to find an acceptable replacement. Nothing that SBS did was particularly “magical,” and most functionality could easily be achieved with custom Linux implementations (Ubuntu Server, CentOS, etc.)
The real trick is to provide a single interface for small business admins who don’t have the time or desire to learn to configure each and every network service. There are a number of open-source alternatives out there, but none really offered the groupware capabilities that Exchange server (bundled with SBS) provided.
Zentyal® is a Linux distro based on Ubuntu Server, that provides a great administrative front-end for easy configuration and management. It also serves as a drop-in replacement for Exchange® server. So you can have all the groupware functionality that you once had with SBS, but with the extra benefit of not being tied to Microsoft!
Havensys Technologies, LLC. has been testing Zentyal Server version 3.3 and I have to say that it is impressive. There is no IPv6 support yet, but the developer claims it is coming soon. If you are looking for a simple-to administer open-source SBS replacement, this is certainly worth looking into. You can download the server distro at:
Zentyal® is a registered trademark of Zentyal S.L. http://www.zentyal.com
Microsoft® and Microsoft Exchange® are registered trademarks of Microsoft Corporation