這是合法且經驗證的作法
https://docs.aws.amazon.com/zh_tw/ses/latest/dg/troubleshoot-receiving.html
https://support.google.com/mail/answer/1311182?hl=zh-Hant#zippy=%2C%E6%88%91%E5%9C%A8%E5%AF%84%E4%BB%B6%E8%80%85%E5%90%8D%E7%A8%B1%E6%97%81%E9%82%8A%E7%9C%8B%E5%88%B0%E9%80%8F%E9%81%8E%E5%AD%97%E6%A8%A3%E5%92%8C%E7%B6%B2%E7%AB%99%E5%90%8D%E7%A8%B1%2C%E6%88%91%E5%9C%A8%E5%AF%84%E4%BB%B6%E8%80%85%E5%90%8D%E7%A8%B1%E6%97%81%E9%82%8A%E7%9C%8B%E5%88%B0%E9%9B%BB%E5%AD%90%E9%83%B5%E4%BB%B6%E5%9C%B0%E5%9D%80