public function connect($username, $password)
    {
        // Get connection parameters
        $host = $this->rc->config->get('managesieve_host', 'localhost');
        $port = $this->rc->config->get('managesieve_port');
        $tls  = $this->rc->config->get('managesieve_usetls', false);

        $host = rcube_utils::parse_host($host);
        $host = rcube_utils::idn_to_ascii($host);

        // remove tls:// prefix, set TLS flag
        if (($host = preg_replace('|^tls://|i', '', $host, 1, $cnt)) && $cnt) {
            $tls = true;
        }

        if (empty($port)) {
            $port = getservbyname('sieve', 'tcp');
            if (empty($port)) {
                $port = self::PORT;
            }
        }

        $plugin = $this->rc->plugins->exec_hook('managesieve_connect', array(
            'user'      => $username,
            'password'  => $password,
            'host'      => $host,
            'port'      => $port,
            'usetls'    => $tls,
            'auth_type' => $this->rc->config->get('managesieve_auth_type'),
            'disabled'  => $this->rc->config->get('managesieve_disabled_extensions'),
            'debug'     => $this->rc->config->get('managesieve_debug', false),
            'auth_cid'  => $this->rc->config->get('managesieve_auth_cid'),
            'auth_pw'   => $this->rc->config->get('managesieve_auth_pw'),
            'socket_options' => $this->rc->config->get('managesieve_conn_options'),
        ));

        // Handle per-host socket options
        rcube_utils::parse_socket_options($plugin['socket_options'], $plugin['host']);

        // try to connect to managesieve server and to fetch the script
        $this->sieve = new rcube_sieve(
            $plugin['user'],
            $plugin['password'],
            $plugin['host'],
            $plugin['port'],
            $plugin['auth_type'],
            $plugin['usetls'],
            $plugin['disabled'],
            $plugin['debug'],
            $plugin['auth_cid'],
            $plugin['auth_pw'],
            $plugin['socket_options']
        );

        $error = $this->sieve->error();

        if ($error) {
            rcube::raise_error(array(
                    'code'    => 403,
                    'file'    => __FILE__,
                    'line'    => __LINE__,
                    'message' => "Unable to connect to managesieve on $host:$port"
                ), true, false);
        }

        return $error;
    }