https://blog.wongcw.com/2022/06/18/ios-16%e4%b8%adapple-mail%e7%8f%be%e5%85%81%e8%a8%b1%e8%b3%bc%e8%b2%b7%e8%87%aa%e5%ae%9a%e7%be%a9%e5%9f%9f%e5%90%8d/
iOS 16中Apple Mail現允許購買自定義域名