You see the the result of "Submission invalid: submitter is not in the submitter allowed list" after submitting spam for the Customer Specific Rule feature of the Messaging Gateway, even though the address has been placed in the allowed submitter list.
This was determined to be an issue with the spam submission infrastructure.
Release : 10.7.4
This issue is currently resolved. If you had experienced this issue, please try again. If the submission continues to fail, please open a technical support case.