Swift_Transport_AbstractSmtpTransport::_sendTo PHP Method

    private function _sendTo(Swift_Mime_Message $message, $reversePath, array $to, array &$failedRecipients)
    {
        if (empty($to)) {
            return 0;
        }
        return $this->_doMailTransaction($message, $reversePath, array_keys($to), $failedRecipients);
    }