The full error is:
Failed to request report
Error:
Error executing request. Invalid notification address or notification address not in accepted domains.
I am using the new Exchange admin center and getting this error when trying to run a message trace for the last 30 days. I am logged into and using an account for our primary domain, and the message trace report was to be delivered to that address. The only thing I can think of was Microsoft prompting to use a secondary/external email address for 2FA, and I added an @gmail.com address. Following this error, I've since removed it and can no longer find any references to the @gmail.com address in Exchange admin center or Microsoft 365 admin center.
I found a thread from June 2021 with someone else experiencing the same issue with seemingly the same circumstances. The Microsoft agent recommended using https://protection.office.com/messagetrace to run the trace and that resolved it for them. However, this method did not work for me.
Any ideas?