public function sendMail($receivers, string $subject, string $template, array $templateParameters = [], $sender = null): int
    {
        try {
            $sender = $this->getSender($sender);
        } catch (InvalidArgumentException $e) {
            $this->logger->error($e->getMessage());

            return -1;
        }

        $body = $this->twig->render($template, $templateParameters + $this->getDefaultTemplateParameters());

        $subject = $this->translator->trans($subject, [], 'ngsite_mail');

        $message = new Swift_Message();

        $message
            ->setTo($receivers)
            ->setSubject($this->siteName . ': ' . $subject)
            ->setBody($body, 'text/html');

        $message->setSender($sender);
        $message->setFrom($sender);

        return $this->mailer->send($message);
    }