[求助]发送邮件后，收件人能收到邮件，但还是有退信通知

meizi0212

最近几天发出邮件后，总收到退信通知，其实对方已经收到了邮件，退信通知如下：<br>
> This is the Postfix program at host mail.8q8.net.<br>
> <br>
> I'm sorry to have to inform you that your message could not be<br>
> be delivered to one or more recipients. It's attached below.<br>
> <br>
> For further assistance, please send mail to <postmaster><br>
> <br>
> If you do so, please include this problem report. You can<br>
> delete your own text from the attached returned message.<br>
> <br>
> The Postfix program<br>
> <br>
> <thmeckey@kanoon.net> (expanded from <sales@meckey.com>): host<br>
> peyk.kanoon.net[217.218.87.3] said: 500 error (in reply to MAIL FROM<br>
> command)<br>
> <br>
> <thmeckey@kanoon.net>: host peyk.kanoon.net[217.218.87.3] said: 500 error (in<br>
> reply to MAIL FROM command)<br>
各位大虾帮忙看看是什么原因，该怎么解决才好，谢谢！<br>