Kolab 3 has built-in ActiveSync support, using Syncroton.
It's integrated into Roundcube, all settings can be done using the Webmail client. Installing it is very easy on Debian Wheezy: apt-get install kolab-syncroton
If Kolab 3 is already installed and configured (setup-kolab already done) the database needs to be imported by hand: mysql -p roundcube < /usr/share/doc/kolab-syncroton/syncroton.sql
If kolab-syncroton is installed before running setup-kolab, the database will be populated with the tables.
To check if ActiveSync is working fine, open http://yourserver/Microsoft-Server-ActiveSync and log-in with an available account. It should display It works! Your userid is: 2 and your IP address is: x.x.x.x., Logs are written to /var/log/roundcubemail and $rcmail_config['activesync_debug'] can be added to main.inc.php to increase logging.
Just add the account to the mobile device and all E-Mails, calendar entries and contacts will be synced. In Roundcube -> Settings -> Activesync the new device should appear and can be individually configured. It's possible to set the device name and choose which folders should be synchronized.
Basically it works great, but there seems to be a bug when synchronizing with a modern Samsung Android device (such as a Galaxy Note or Galaxy S3). All E-Mails are marked as encrypted and can't be read. A Bugreport about this is already filled. Another problem I found is synchronizing contacts with a Nokia N9. It seems not possible. Maybe SyncEvolution will do it.
