The email could not be delivered because the receiving domain is not configured in accordance with RFC.
We expect an MX record which itself has a valid A record.
If the domain was specified incorrectly, this may already be the cause, otherwise the DNS records must be checked and corrected by the person responsible for the domain.
For more information, see the RFCs at the following links:
If you have any questions or require further support, please contact the administrator of the recipients domain.
Please note that in the case of inquiries to our postmaster team, a reply to your domain is not possible if your domain is the same as the RCPT TO domain and the misconfiguration still exists. In such cases, please provide an alternative email contact address of another domain.
See also: General information on our error messages.