function change_mailbox_password($mailbox, $newpass)
    {
        list($user, $domain) = explode("@", $mailbox);
        $domain_id = $this->get_domain_id($domain);

        // if domain cannot be resolved to an id, do not continue
        if (!$domain_id) {
            return false;
        }

        // build xml-packet
        $request = $this    -> get_request_obj();
        $mail    = $request -> addChild("mail");
        $update  = $mail    -> addChild("update");
        $add     = $update  -> addChild("set");
        $filter  = $add     -> addChild("filter");
        $filter->addChild("site-id", $domain_id);

        $mailname = $filter->addChild("mailname");
        $mailname->addChild("name", $user);

        $password = $mailname->addChild("password");
        $password->addChild("value", $newpass);
        $password->addChild("type", "plain");

        $packet = $request->asXML();

        // send the request to plesk
        $res = $this->send_request($packet);
        $xml = new SimpleXMLElement($res);
        $res = strval($xml->mail->update->set->result->status);

        return $res == "ok";
    }