I've been using Thunderbird for my hotmail.com and cox.net accounts for many years. Recently cox transitioned to yahoo.com with their email and users had to transition over. I was able to do this for 5 accounts - no problem. My hotmail.com was a bit more of a challenge but I was able to get it to work. Last week I started getting sign-in errors. Nothing worked and I deleted my hotmail.com address in Thunderbird figuring it would be better to just start over - wrong choice. Now I cannot even install my hotmail.com account on my Thunderbird. I first tried the straightforward approach. Get an app password from my Microsoft account. Nest I it account actions, add email account. I added my name, email address and app password. When I hit ok a message quickly flashed saying configuration doesn't work. When I done I get a message that server already exists. I tried going to manual configuration and changed to normal password but got the message again that server exists. I went to the Outgoing server (SMTP) list but the outlook server doesn't show up.I tried using the hotmail password instead og the app password with same results. Finally I logged out of Thunderbird, turned off the two party requirement in Outlook and again tried to add the account to Thunderbird. Now I get the message 'could not get issuer fot oauth2 authentication'. I next went into manual configuration, turned authentication to 'normal password' the the hotmail account installed. I closed Thunderbird and started again. sent a message to the hotmail account and had to reenter the password - works. Tried to send a message and was asked againgn for the app password - then it works. So all is good except when I check the server settings for smtp and IMAP, ot shows 'normal password' After strugglig for two hours I do not want to risk changing them to oauth2. Checked under 'saved logins' and the app password is shown. Is it likely that I have arrived at a stable solution? What am I risking by having the 'normal password' authentication?