I've just set up Thunderbird on my dad's Windows PC, but I can't figure out how to set up signatures. In Outlook Express, he had a signature set up somewhere, so that he could click a "Sign" toolbar button to add a signature to his messages. Unfortunately, I can't figure out how to do this in Thunderbird. The only signature options I can find ask me to browse for a file (a text file containing the signature?), but I can't figure out how to add a Sign button to the toolbar or anything like that - it seems to want to add a signature to *every* message! So how can I selectively add signatures to messages?