Okay, jumped some hoops for m$ to try and get my email working, but no joy, sender.office.com reports the IP is not blocked and suggests I refer to bounce error

Okay, jumped some hoops for m$ to try and get my email working, but no joy, sender.office.com reports the IP is not blocked and suggests I refer to bounce error (there is no bounced message), I tried the Outlook mitigation route, and after 24 hours received a "Not qualified for mitigation ... Our investigation has determined that the above IP(s) do not qualify for mitigation." message (my stars). Today I've joined the Microsoft Smart Network Data service, and that reports the IP of the mailserver as having normal service, so where now ? PM Bill?