MailManager::doMail

public MailManager::doMail($module, $key, $to, $langcode, $params = array(), $reply = NULL, $send = TRUE)

public function doMail($module, $key, $to, $langcode, $params = array(), $reply = NULL, $send = TRUE) {
  $site_config = $this->configFactory->get('system.site');
  $site_mail = $site_config->get('mail');
  if (empty($site_mail)) {
    $site_mail = ini_get('sendmail_from');
  }

  // Bundle up the variables into a structured array for altering.
  $message = array(
    'id' => $module . '_' . $key,
    'module' => $module,
    'key' => $key,
    'to' => $to,
    'from' => $site_mail,
    'reply-to' => $reply,
    'langcode' => $langcode,
    'params' => $params,
    'send' => TRUE,
    'subject' => '',
    'body' => array(),
  );

  // Build the default headers.
  $headers = array(
    'MIME-Version' => '1.0',
    'Content-Type' => 'text/plain; charset=UTF-8; format=flowed; delsp=yes',
    'Content-Transfer-Encoding' => '8Bit',
    'X-Mailer' => 'Drupal',
  );
  // To prevent email from looking like spam, the addresses in the Sender and
  // Return-Path headers should have a domain authorized to use the
  // originating SMTP server.
  $headers['Sender'] = $headers['Return-Path'] = $site_mail;
  $headers['From'] = $site_config->get('name') . ' <' . $site_mail . '>';
  if ($reply) {
    $headers['Reply-to'] = $reply;
  }
  $message['headers'] = $headers;

  // Build the email (get subject and body, allow additional headers) by
  // invoking hook_mail() on this module. We cannot use
  // moduleHandler()->invoke() as we need to have $message by reference in
  // hook_mail().
  if (function_exists($function = $module . '_mail')) {
    $function($key, $message, $params);
  }

  // Invoke hook_mail_alter() to allow all modules to alter the resulting
  // email.
  $this->moduleHandler->alter('mail', $message);

  // Retrieve the responsible implementation for this message.
  $system = $this->getInstance(array('module' => $module, 'key' => $key));

  // Format the message body.
  $message = $system->format($message);

  // Optionally send email.
  if ($send) {
    // The original caller requested sending. Sending was canceled by one or
    // more hook_mail_alter() implementations. We set 'result' to NULL,
    // because FALSE indicates an error in sending.
    if (empty($message['send'])) {
      $message['result'] = NULL;
    }
    // Sending was originally requested and was not canceled.
    else {
      // Ensure that subject is plain text. By default translated and
      // formatted strings are prepared for the HTML context and email
      // subjects are plain strings.
      if ($message['subject']) {
        $message['subject'] = PlainTextOutput::renderFromHtml($message['subject']);
      }
      $message['result'] = $system->mail($message);
      // Log errors.
      if (!$message['result']) {
        $this->loggerFactory->get('mail')
          ->error('Error sending email (from %from to %to with reply-to %reply).', array(
            '%from' => $message['from'],
            '%to' => $message['to'],
            '%reply' => $message['reply-to'] ? $message['reply-to'] : $this->t('not set'),
          ));
        drupal_set_message($this->t('Unable to send email. Contact the site administrator if the problem persists.'), 'error');
      }
    }
  }

  return $message;
}