Meanwhile I like the horde webmail suite very much. It provides webmail, calendar, todo, contact and can sync via SyncML, ActiveSync and supports caldav (or webdav... never really sure). Anyway, I'd like to make horde available on all domains at /horde. So I looked how phpmyadmin and squirrelmail are being handled. If found that those are stored in /etc/apache2/sites-available/ispconfig.conf Code: <Directory /usr/share/phpMyAdmin> Order allow,deny Allow from all </Directory> <Directory /usr/share/squirrelmail> Order allow,deny Allow from all </Directory> Because of that, I thought I should add the horde info also there. So I added: Code: Alias /Microsoft-Server-ActiveSync /var/www/horde/rpc.php Alias /horde /var/www/horde <Directory /var/www/horde> Options +FollowSymLinks AllowOverride None order allow,deny allow from all php_value include_path ".:/usr/share/php" php_value open_basedir "none" php_value upload_tmp_dir "/var/www/horde/phptmp/" </Directory> After I restarted the webserver and used one of the domain I added, I got this error: [Sun Mar 18 17:24:21 2012] [error] [client 127.0.1.1] SoftException in Application.cpp:221: File "/var/www/horde/index.php" is not in document root of Vhost "/var/www/clients/client1/web1/web" However when I open it using the ip: http://ip_address/horde or http://hostname.com/horde it works.