If I ever do start using that address again, I guess I'd have to digitally sign the mail. Of course, going down that route would be useless unless other people also learned to use cryptography, something I am basically convinced will never happen. It requires thinking and effort, you know.

Most people would resist it as strongly as they could.

The nature of email as used by most people today is such that there is no authentication whatsoever. It is trivial to send mail claiming to be somebody else. That's what happened in my case. I don't see that changing any time soon either.