I’m trying to setup an outlook.office365.com account and followed the instructions in How do I add an Office365 account?
In step 7, my browser opens and redirects to microsoftonline.com which is a non-registered domain. I’ve tried many different DNS servers, none of them does resolve that domain.
I’m using the same settings on Thunderbird on my desktop with OAuth2 authentication, and there it works as expected.
Any idea, what could be the reason why this is going wrong?
Ah, found out that on desktop, this doesn’t redirect to microsoftonline.com but to login.microsoftonline.com, so I wondered why that wasn’t happening on the mobile.
Turns out, my e/OS on the mobile comes with Advanced Security pre-configured and when I turn off the Tracking protection there, then the verification works.
Just discovered, that this problem not only occurs during authentication, also later when trying to fetch messages, while the advanced security for trackers is enabled, it doesn’t work.
Just digged deeper and there is a tracker called “Mobile Engagement” (see εxodus) which prevents K9 from interacting with office365 when blocked. So I accepted an exception for that tracker and now everything seems to work.
Maybe that information also helps others.