protected function connect($host) {

        $remote_socket = $host . ':' . $this->connect_port;

        $errnum = 0;

        $errstr = '';

        $this->host = $remote_socket;

        // open connection

        $this->socket = @stream_socket_client(

            $this->host,

            $errnum,

            $errstr,

            $this->connect_timeout,

            STREAM_CLIENT_CONNECT,

            stream_context_create(array())

        );

        // connected?

        if (!$this->connected()) {

            throw new SMTP_Validate_Email_Exception_No_Connection('Cannot ' .

            'open a connection to remote host (' . $this->host . ')');

        }

        $result = stream_set_timeout($this->socket, $this->connect_timeout);

        if (!$result) {

            throw new SMTP_Validate_Email_Exception_No_Timeout('Cannot set timeout');

        }

    }