pino-8.x-1.2-no-core/modules/member_mailer/member_mailer.module

<?php

/**
 * @file
 * Contains member_mailer.module.
 */

use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function member_mailer_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the member_mailer module.
    case 'help.page.member_mailer':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Mailer for Member entities') . '</p>';
      return $output;

  }
}

/**
 * Implements hook_mail().
 */
function member_mailer_mail($key, &$message, $params) {
  switch ($key) {
    case 'member_mail':
      $message['from'] = $params['from'];
      $message['subject'] = $params['subject'];
      $message['body'][] = $params['message'];
      break;
  }
}