Email routing not forwarding

Receiving an automated email reply that the user doesn’t exist. When I view the Activity Log, it’s showing that the Delivery Failed, and the rejected reason refers to the old email MX record. I’ve verified that the old MX records have been removed, and the Configuration Summary indicates that everything is enabled and configured.

Rejected Reason: upstream (previous. email. mx-record. com) error: failed to initalize: Unknown error: permanent error (550): Verification failed for <cfbounces+ndrdrop@ mydomain .com>No Such User Here"Sender verify failed