smtp.module

<?php

/**
 * @file
 * Enables Drupal to send e-mail directly to an SMTP server.
 *
 * This module uses a customized extract of the PHPMailer
 * library (originally by Brent R. Matzelle, now maintained
 *  by Codeworx Tech.) relicensed from LGPL to GPL, included
 * as a part of the module.
 *
 * Overriding mail handling in Drupal to make SMTP the default
 * transport layer, requires to change the 'system.mail.interface'
 * default value array('default' => 'Drupal\Core\Mail\PhpMail').
 * This module uses array('default' => 'SMTPMailSystem').
 */

use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function smtp_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.smtp':
      return t('Allow for site emails to be sent through an SMTP server of your choice.');
  }
}

/**
 * Implements hook_menu().
 */
function smtp_menu() {
  $items['admin/config/system/smtp'] = [
    'title' => 'SMTP Authentication Support',
    'description' => 'Allow for site emails to be sent through an SMTP server of your choice.',
    'route_name' => 'smtp.config',
  ];
  return $items;
}

/**
 * Implements hook_mail().
 */
function smtp_mail($key, &$message, $params) {
  if ($key == 'smtp-test') {
    $message['subject'] = $params['subject'];
    $message['body'] = $params['body'];
  }
}

/**
 * Implementation of hook_queue_info().
 */
function smtp_queue_info() {
  $queues['smtp_send_queue'] = [
    'worker callback' => 'smtp_send_queue_runner',
    'cron' => [
      'time' => 60, // This is the max run time per cron run in seconds.
    ],
  ];
  return $queues;
}

/**
 * smtp_send_queue queuer.
 */
function smtp_send_queue($mailerObj) {
  $queue = Drupal::queue('smtp_send_queue');
  $queue->createItem($mailerObj);
}

function smtp_send_queue_runner($variables) {
  _smtp_mailer_send($variables);
}

function _smtp_mailer_send($variables) {
  $mailer = $variables['mailer'];
  $to = $variables['to'];
  $from = $variables['from'];

  $logger = \Drupal::logger('smtp');

  // Let the people know what is going on.
  $logger->info('Sending mail to: @to', ['@to' => $to]);

  // Try to send e-mail. If it fails, set watchdog entry.
  if (!$mailer->Send()) {
    $logger->error('Error sending e-mail from @from to @to: @error_message', ['@from' => $from, '@to' => $to, '@error_message' => $mailer->ErrorInfo]);
    return FALSE;
  }

  $mailer->SmtpClose();
  return TRUE;
}