This may help, or not. To clarify, thunderbird did not request your password, your email provider did. Thunderbird is just your agent. In an attempt to clear the setup, do this: - check that your password works properly when logging on via website. That's just a sanity check. - in thunderbird, click settings>privacy&security - click saved passwords and then show passwords - now, highlight the rows for the account (normally two) and delete them. This removes whatever passwords were stored. - close and restart thunderbird and try again with the right password. - if that does not work, it may be that your email provider requires an 'app' password instead of the normal password when using a PC email client. Gmail is an example of this.