For several days I have received several emails with the following:

This message was created automatically by mail delivery system.

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

The original message was received at Thu, 25 Feb 2021 04:46:36 -0800 from

xxxxx@xxxx.pt

     ----- The following addresses had fatal errors -----

    [xxxx.xxxxx@xxx.xx]

Message will be retried for 4 more day (s)

What can I do