>...always encrypts with their private key, and anyone you want to hear from, you add their public key to your list of keys you decrypt to read. I think you me

>...always encrypts with their private key, and anyone you want to hear from, you add their public key to your list of keys you decrypt to read. I think you mean that posters would sign with their private keys and you would have a list of public keys that you would verify the signature against. That, incidentally, is also a valid approach to email spam...