Failed to Receive Mail from A Client

rardark

Hello Everyone,

I have a client from Italy suddenly cannot send email to me and he receives a bound back immediately stating “550 5.1.1 invalid destination domain”. However, I can receive mail sent from other clients. So is it the problem of his side? Thank you!

esackbauer

As we cannot see the NDR (bounce mail) or the postfix log of the connection attempt we can only guess.
My guess would be client has a typo in email address.

rardark

esackbauer Thanks for the reply! He showed me the bounce mail and he typed the email address correctly. However, we didn’t see any log from our side about the email he sent. So the only thing we can do from now is to ask him to check the send out records from his side for further investigation?

esackbauer

rardark In the bounce mail there is the IP address which server caused the bounce. Was it the one of your mailcow? If not then the problem is probably DNS records. Are you using IPv6 and IPv4?