向一个邮箱发了很多封系统一直会发来一封英文信，意思就是这封邮件出现错误什么的，不能成功发送，并且这封英文信的附件就是我刚刚发的邮件。英文邮件就是这个：I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
但是查看 已发送邮件 那几封邮件的状态是发送成功
请问这到底是怎么回事？
