In general, when Thunderbird suddenly starts asking for a password, there is nothing wrong with a stored password or anything else in Thunderbird, but the email provider either requires some changed authentication setting such as an additional [https://support.microsoft.com/en-us/help/12409/microsoft-account-app-passwords-two-step-verification "app password"], or the email server has (temporary) issues. The latter is very common for Hotmail, and using webmail does not guarantee the issue is caused by the email client - that’s a web interface, communicating differently than POP/IMAP email servers. The Hotmail/Outlook servers status can be checked [http://downdetector.com/status/outlook here]. Most likely, you would need to change the incoming and outgoing mail server settings in Thunderbird to outlook.office365<!-- -->.com and smtp.office365<!-- -->.com respectively, and leave everything else unchanged. ''bdaustin [[#question-1173683|said]]'' <blockquote> I then deleted this account to try to re-add it but now I can't even add it as Mozzila recognizes some other password that I don't know. </blockquote> This part I don’t get. When does Mozilla (or in fact Thunderbird) ask for / offer a password and in what step?