Thunderbird does not provide any way to create signature files. Use your operating system tools to create them—for example, use a plain text editor.

Thunderbird does not provide any special place to store signature files.

You could create a Signatures directory in your profile to store them, making them easy to back up along with the rest of your profile. Or you could store them somewhere else.

You can get more information regarding this aspect by clicking the link below

http://kb.mozillazine.org/Signatures_(Thunderbird)