I presume you are wanting to backup your profile folder. If you have POP mail accounts or emails in 'Local Folders', all emails will be in the Profile folder by default. If you have IMAP mail accounts, to make sure you have a copy in your Thunderbird Profile folder; synchronise your subscribed folders for offline use to get a copy into Thunderbird profile folder. Good links with info: * http://kb.mozillazine.org/Profile_backup * http://kb.mozillazine.org/IMAP_backup * https://support.mozilla.org/en-US/kb/profiles-tb If you find you cannot locate /see anything in 'appdata' folder, this is because they are hidden by default. * http://kb.mozillazine.org/Show_hidden_files_and_folders