I've installed horde webmail to /var/www/webmail .
No I've add a symlink to it in the web part
No I become this error, when I want to open mydomain.de/webmail
Warning: Unknown: open_basedir restriction in effect. File(/var/www/mydomain/web/webmail/index.php) is not within the allowed path(s): (/var/www/clients/client1/web4/web:/var/www/clients/client1/web4/tmp:/usr/share/php5) in Unknown on line 0
Warning: Unknown: failed to open stream: Operation not permitted in Unknown on line 0
Fatal error: Unknown: Failed opening required '/var/www/mydomain/web/webmail/index.php' (include_path='.:/usr/share/php:/usr/share/pear') in Unknown on line 0