I’m seeing the same thing. Last week the webmail sending through O365 gave the message you posted. Then when I removed it and try to add it back in I get and authorization failure. If I dig into my Microsoft account I can see there QuickBooks connector there as an authorized app, and when I click on it says something about the URL being invalid. I just had a customer call with QB Enterprise with the same problem. It seems like the QuickBooks to Microsoft (webmail) authorization is broken at the moment.