Question 442 Unable to deliver message within specified time

[D4NY]

In the last days i've received notice that on one domain hosted on our Plesk server there is a problem receiving mails from a specified domain.
This is the delivery error message:

Original-Recipient: <xxx.yyy@wwwww.com>
Action: failed
Diagnostic-Code: smtp; 442 Unable to deliver message within specified time.
Remote-MTA: 51.xxx.yyy.zzz

From others domains it's working, so the question is if it's possible that the problem is by our side and not from the sender (that is a big insurance company).

 

[Hex]

It's hard to think about email issues without server information, it could be anything from DNS MX to network issue and expired certificate.

If you're sure about the MX record for both sender domain and recipient domain.. check the recipient inbox storage capacity it could be full and rejecting new emails.