Thunderbird oAuth2 connection to Azure AD app

     Also via Config Editor removed all 4 entries with *auth2.scope at the end.

Dear support, I am an Azure AD admin and recently we have been receiving ticket that some users cannot connect with they Thunderbird clients to our Exchange Online mailboxes. Because MS turn off the basic authentication I had to created/register an Azure app with the normal API permissions for POP,IMAP,offline_access and SMTP. After that in 2023 January I also had to delete and register again the app because of a major change. Everything fine until now, where I did try it also out and the account is not connecting to the exchange online server. I followed you article precisely and did all the steps but no success: https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202 1 - Delete the app and re-registered via the Link and as admin I have granted it to the entire company 2 - I did make a clean install of Thunderbird and deleted all profiles and created a new one. Also via Config Editor removed all 4 entries with *auth2.scope at the end. I've spent 5 hours trying to make it work. Is the connection to M365 still supported ? best regards, Mihai