[tomjen2]

As long as you are only sending charectors on the paper, you might be right, but you can send physical items in a letter - unlike in an email.

And the set of people I want to send mail to intersected with the set of people who have the faintest idea what public/private keys are is the empty set. So that won't fly.

In addition, the fact that I am willing to pay a dollar to send a message is a statement that you might want to take five seconds to look at the letter, whereas most emails aren't worth taking a look at.