I have to proxy a site which is hosted on an external webspace through my lighty on example.org. My config so far:

$HTTP["url"] =~ "^/webmail" {
    proxy.server =  ("/webmail/" => (
        # this entry should link to example2.org
        ("host" => "1.2.3.4", "port" => 80)
    ))
}

The webspace provider has configured my domain as vhost. So if i access http://1.2.3.4/webmail/ lighttpd will only deliver the main site of the webspace provider which says "Site example.org was not found on our server."

Any suggestions how i have to configure lighty to proxy sites that are only hosted as vhost (and do not have an ip on their own)?