So, suddenly Thunderbird stopped downloading my Hotmail emails saying password was invalid. I use POP settings and realise that two step authentication can be a problem but even deleting the old password in the password manager and obtaining a new app password doesn't work. I've also tried turning my antivirus (Avast) off to no effect. Is there something I need to do in the troubleshooting side of Thunderbird before I can resubmit the new Hotmail password? By the way it seems to work with IMAP settings but not the POP settings.