Overnight, while computer was sleeping, Thunderbird appears to have forgotten the email password. A dialog box pops up when checking email "login to server pop.centurylink.net with username {correct email address displayed} failed." With options retry, enter new password, and cancel available. Retry simply loops back to this error. Entering the (verified) correct password has no positive impact at all. Program and computer rebooted, no change. Windows 11 Pro. Password was not recently changed.