Horde Webmail is even more of a collaborative framework of services. And since June 14, a new version of Horde is out. This is the version 4, which is a major new release.
The following new features and changes improved overall Horde 4 performance.
* Completely rewritten in php 5
* New installation procedure through a PEAR installer
* Simplifying the configuration process
* Support for ActiveSync
* Layout without frames
* Group preferences
* Improving the cache and reducing the size of the sessions.
* Shared libraries are faster
* Reducing dependencies on external libraries
* Many miscellaneous improvements.