然後用Gmail寄信做測試
寄出後就會收到
Delivery Status Notification (Failure)
Delivery to the following recipient failed permanently:
et54987@b.com.tw
Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain b.com.tw by IP
The error that the other server returned was:
550 M.5 <et54987@b.com.tw>... User unknown(Local Mailbox)