发往德国和新加坡邮件有退信？

luweionline

以下是退信信息，谁能帮我分析一下什么原因，前几天还可以呢？ 谢谢
> I'm afraid I wasn't able to deliver your message to the following address.
> This is a permanent error; I've given up. I am sorry for this
inconvenience.
>
> daniela.saccento@odenwald-chemie.de Error Message: 554 cannot resolve MX
record for odenwald-chemie.de
>
> michael.feist@odenwald-chemie.de Error Message: 554 cannot resolve MX
record for odenwald-chemie.de