public function getHandlers()
    {
        $handlers = &gplcart_static('mail.handlers');

        if (isset($handlers)) {
            return $handlers;
        }

        $handlers = (array) gplcart_config_get(GC_FILE_CONFIG_MAIL);
        $this->hook->attach('mail.handlers', $handlers, $this);
        return $handlers;
    }