We are using exchange with outlook 2016 and been asked for credentials since yesterday.
It seems that the used mailadress in outlook is also registered at office.com for some reason.
After entering the password from office.com the login-mask from outlook won't return but outlook still says that it is not connected to exchange. After clicking the information at the bottom it changes immediatly to "online with exchange".
We also updated our office to the newest version, but the error ist still there.
Restarting doesn't solved the problem, either. And therefore the starting process last at least 5 minutes.
It seems that outlook looks somewhere for my account but can't find any.
Can any proof this behaviour or solve?