Instead of trying to filter spam, why not require every email sender to post a tiny (pennies) bond, which can be “seized” by the recipient if the message was unwelcome? Marshall W. Van Alstyne of Boston University & MIT lays out the design, and the argument for it, in “Curing Spam: Rights, Signals & Screens” in the latest Economists’ Voice (Vol. 4 : Iss. 2, Article 4) from Berkeley Economic Press.
This seems like an obviously good idea, and as I recall it shows up (for phone calls rather than email) in one of the Heinlein books. Van Alstyne says it’s already available commercially, but doesn’t go into detail.
The problem seems to me as obvious as the opportunity. There’s no problem with commercial email, but what about messages from actual people sending from Hotmail, Yahoo, GMail, or other free accounts? Yes, I suppose it could be charged back the sender through his ISP, but what if someone is on the road and using someone else’s computer?
Does anyone have experience with such a system? And can we institute it for phone calls, which are much more annoying than emails?