Yesterday, thunderbird 115.3.1 was automatically installed. Since then, all my Microsoft accounts do not work anymore. I think the problem is this: https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202. I've been messing around with the imap url, smtp server and oauth2 settings for a day now, without fixing the problem. I have one profile with multiple e-mail accounts (more than 10, under which gmail, hotmail, live and outlook accounts) in it. They used to authenticate with oauth2, but now I cannot get that to work anymore. I can get receiving mail to work (even with oauth2), but sending mail (smtp server settings) are behaving different and unexpected every time. Some accounts can send an e-mail, and after restarting thunderbird not anymore. Other accounts have not been able to send an e-mail at all. I'm talking, for instance about 2 Live mail address behaving differently, even with the same settings (url, protocol etc). Another major pain is the following (and I've not read about other people having that same problem, yet): I've logged into the outlook popup and given the thunderbird app access rights again, but after restarting thunderbird about the half of those credentials are gone again (in thunderbird settings Saved password). And I can start all over again? What can I do?!