Rated 5 out of 5 stars

Perfect! I have been waiting for this for years. I don't want to attach the signature to each email but need to do it from time to time. This extension allows me to do exactly that. For it to work, you have to type your signature in the "signature text" (use HTML format for better formatting), and check the "attach the signature from a file instead" box below (which is equivalent as setting the "true" value in the .js file). However, you have to select a signature file that does not exist (e.g. I renamed the file after selecting it) otherwise you will get duplicate signatures. It sounds strange but that's how it works.

This review is for a previous version of the add-on (0.2).