AUP#SNDR blocking
AUP ==> Appropriate Usage Policy SNDR ==> The E-mail ID in the "From:" field of messages that you are sending. BLOCKING ==> E-mail filters are keying on that ID.
Test: If you use an E-mail client, such as Windows Mail, or Microsoft Outlook, or Thunderbird, temporarily change the value in the "From:" field to your spouse's ID, and forward a message to your spouse's ID. Is the message received by your spouse? Remember to "undo" this change.
If it is received, then I recommend that you contact and tell us of the results of your experiment, and ask them to remove the "block" against your E-mail ID.
Note that it could be a spammer who is sending thousands of "spam" messages, but who is injecting your E-mail ID into the "From:" field of those messages. Our E-mail filters could be blocking that spammer's attempts to abuse your E-mail ID, but leaving you as "collateral damage".