Smtp::exchange

protected function exchange($data, &$error)
{
	$error = null;

	if ($this->sendData(sprintf("%srn", $data)) === false)
	{
		$error = Smtp::ERR_COMMUNICATE;
		return false;
	}

	$response = $this->readResponse();

	if ($response === false)
	{
		$error = Smtp::ERR_COMMUNICATE;
		return false;
	}

	if (!preg_match('/^ [23] d{2}  /ix', end($response)))
	{
		$error = Smtp::ERR_COMMAND_REJECTED;
	}

	return $response;
}