public function addContentToMailer($message, $code, $data, $plainOnly = false)
    {
        if (isset($this->templateCache[$code])) {
            $template = $this->templateCache[$code];
        }
        else {
            $this->templateCache[$code] = $template = MailTemplate::findOrMakeTemplate($code);
        }

        if (!$template) {
            return false;
        }

        $this->addContentToMailerInternal($message, $template, $data, $plainOnly);

        return true;
    }