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 we recommend that you contact and tell us of the results of your test, and ask 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".