Signing E-mail with GPG

I started signing most¹ of my e-mail. Why? Nobody else will bother to check the signature. I don't send anything "important" via e-mail. What is the point?

I guess it's become a matter of principle. I am who I say I am, and I can get fairly close to proving it. If you want to check, you can verify who I say I am. All that and it's become really easy.

Why not sign your e-mail?

¹ Most usually being to people who won't freak out when they see the GPG signature in the e-mail.