In order to back up your profile, close Thunderbird, if it is open and then copy the profile folder to another location.
- Shut down Thunderbird.
- Locate your profile folder, as explained in this article.
- Go to one level above your profile’s folder, i.e. to %APPDATA%\Thunderbird\Profiles\
- Right-click on your profile folder (e.g. default), and select Copy.
- Right-click the backup location and select Paste.