class SystemSendEmail

class SystemSendEmail extends RulesActionBase implements ContainerFactoryPluginInterface {
    
    /**
     * The logger channel the action will write log messages to.
     *
     * @var \Drupal\Core\Logger\LoggerChannelInterface
     */
    protected $logger;
    
    /**
     * @var \Drupal\Core\Mail\MailManagerInterface
     */
    protected $mailManager;
    
    /**
     * Constructs a SystemSendEmail object.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin ID for the plugin instance.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\Core\Logger\LoggerChannelInterface $logger
     *   The Rules logger channel.
     * @param \Drupal\Core\Mail\MailManagerInterface $mail_manager
     *   The mail manager service.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, LoggerChannelInterface $logger, MailManagerInterface $mail_manager) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->logger = $logger;
        $this->mailManager = $mail_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('logger.factory')
            ->get('rules'), $container->get('plugin.manager.mail'));
    }
    
    /**
     * Send a system email.
     *
     * @param string[] $to
     *   Email addresses of the recipients.
     * @param string $subject
     *   Subject of the email.
     * @param string $message
     *   Email message text.
     * @param string|null $reply
     *   (optional) Reply to email address.
     * @param \Drupal\Core\Language\LanguageInterface|null $language
     *   (optional) Language code.
     */
    protected function doExecute(array $to, $subject, $message, $reply = NULL, LanguageInterface $language = NULL) {
        // ORIG.
        $langcode = isset($language) ? $language->getId() : LanguageInterface::LANGCODE_SITE_DEFAULT;
        // @todo Is this better?
        $langcode = isset($language) && $language->getId() != LanguageInterface::LANGCODE_NOT_SPECIFIED ? $language->getId() : LanguageInterface::LANGCODE_SITE_DEFAULT;
        $params = [
            'subject' => $subject,
            'message' => $message,
        ];
        // Set a unique key for this email.
        $key = 'rules_action_mail_' . $this->getPluginId();
        $recipients = implode(', ', $to);
        $message = $this->mailManager
            ->mail('rules', $key, $recipients, $langcode, $params, $reply);
        if ($message['result']) {
            $this->logger
                ->notice('Successfully sent email to %recipient', [
                '%recipient' => $recipients,
            ]);
        }
    }

}