I want societal expectations and systems to support the following.

I'll be glad to read a message from a stranger for a price. After my escrow agent informs me my message reading fee has been placed in escrow, I'll gladly look at the message. If I don't like the message, I'll cash your check. No problem! If I like the message, depending on how much I like it, I'll leave the money in escrow or refund it; and if I reply, I may send you an unguessable email address for future free correspondence.

Friends and relatives would have each have an unguessable email addresses for me (and presumably each other).

This would enable folks without a personal assistant to be reachable yet not open themselves up to the spamming scum of the earth.

This would be useful for social networking sites that focus on professional relationships, like LinkedIn.

It's essential that the terms be set by the recipient.