Implements hook_mail().
function system_mail($key, &$message, $params) {
$token_service = Drupal::token();
$context = $params['context'];
$subject = $token_service
->replace($context['subject'], $context);
$body = $token_service
->replace($context['message'], $context);
$message['subject'] .= str_replace(array(
"\r",
"\n",
), '', $subject);
$message['body'][] = $body;
}