protected function isUsingQueue()
    {
        // It impossible to get either the email is sent out straight away
        // when the mailer is only push to queue, in this case we should
        // assume that sending is successful when using queue.

        $queue = false;
        $driver = 'mail';

        if ($this->memory instanceof Provider) {
            $queue = $this->memory->get('email.queue', false);
            $driver = $this->memory->get('email.driver');
        }

        return $queue || \in_array($driver, ['mailgun', 'mandrill', 'log']);
    }