Please understand, Thunderbird is but a messenger. It's not dissimilar from asking your mail carrier why your mortgage check bounced, despite being properly addressed and stamped. All we know is that the server denied the password, using the account setup that you provided. The 'good news' is that we will try to assist. Please share info on the account's setup server info, and whether this was working yesterday and not today. Whatever seems useful will be appreciated. Thank you.