I'm personal Teamviewer user for years now, however it stopped months ago that I can get emails (I'm using Exchange Online Protection from Office 365). So I could not get any verification email anymore when I added a new computer. I first thought, for sure that is an issue on my side. So I started my Message Trace and saw, that this not even hit the external server. I did not further wonder, until I wanted to subscribe for the Jobs-Newsletter and again, I did not get any emails. I tried to subscribe for very different email-adresses all on somewhere Office 365 but NONE of them got through. I even opened up a ticket on Office 365 but they need an NDR from the Teamviewer team.
I'm just wondering because that could hit everyone who is using Office 365 - maybe your internal IT admin team could have a look on that because I think there might be a chance, that this issue is on your side.