Yes, usernames are almost invariably the email address, usually the whole thing, sometimes just the "local part" before the '@'. Is the old computer still available? Passwords stored in Thunderbird can be seen under: '''[http://kb.mozillazine.org/Menu_differences_in_Windows,_Linux,_and_Mac Tools|Options]|Security|Passwords→Saved Passwords''' If you can't do this, I guess you have to go to your email provider and arrange to re-set the password.