Are you looking for an open source, Web-based e-mail and groupware suite with its own development framework, Ajax interface, more than 50 applications, an active developer community, and millions of end users all over the world? The Horde communication and collaboration suite may not be as well known as the big name commercial offerings, but according to lead developer and release manager Jan Schneider it has just as much to offer, and more.
My first experiences with HORDE were many years ago, and I remember it being a very basic email client at best. Since I switched to Squirrelmail, I never looked back. So it was a surprise to see that the “HORDE application framework” consisted of so many applications. It appears that HORDE is able to hang with other full-featured Linux clients, and potentially extend them via their massive list of HORDE drop in applications.
Support for standards like WebDAV, SyncML, and in a near future release, CalDAV, was a surprise for me, as was the newly Ajax-ified interface. Because HORDE has matured into a full framework, running apps based on the framework is easy, so installing everything from a guestbook to a wiki is not only quick and painless, but managed via a centralized framework.
If you are a network admin for a small company needing an inexpensive but extensible web solution, HORDE might be worth a second look.