I'm getting the above message when attempting to add one of our trading partners' domain to the Allowed Domains list for the Anti-Spam inbound policy in the Office 365 Security & Compliance portal. I'm able to get to the Manage allowed domain window and click the "+". I then enter, e.g., newalloweddomain.com
, hit [ENTER]
(or click the "tooltip" box) to have it show up below the textbox, and click the Add domains button at the bottom.
Then I click Done. I'm able to complete all of these steps without error but, when I click the final Save button on the main Allowed and blocked senders and domains screen, I get the error mentioned above (and displayed in this screenshot):
I've tried with a few different domains - both real and bogus - all resulting in the same error. I've tried adding a "dummy" specific address to the Allowed Senders list and get the same thing. I've also checked to confirm that the domain name I'm trying to add is not already in the allowed list. I've even gone through the other allowed and blocked lists to ensure that neither the domain nor any specific address using that domain is listed in any of them. I've added domains and individual addresses to these lists in the past without issue using this portal (although they've obviously "updated" it since the last time I was in there), so I'm not sure where else to look for potential settings conflicts. What other Office 365 administration settings might be causing this conflict?