POP3 (via SSL/TLS port 995 with "Normal" password) logins for outlook.office365.com stopped working for me this morning. I gather this may be a gradual deprecation of POP3 by MS: https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online Not sure why it took so long to get around to my account. Trying to switch to OAuth2 as recommended there, however I get an incompletely rendered login screen (see image) when setting up OAuth2. I followed the steps in this article: https://support.mozilla.org/en-US/kb/automatic-conversion-google-mail-accounts-oauth20 ... however I was already accepting all cookies and had JavaScript enabled. The URL works when pasted into a browser, but is unable to redirect back to Thunderbird via localhost to complete the process once the authentication is completed. Any suggestsions appreciated!