I really like this idea because it has a sassy, unusual, creative and useful logical structure. As we know, a weakness in all free-entry point systems (like em

I really like this idea because it has a sassy, unusual, creative and useful logical structure. As we know, a weakness in all free-entry point systems (like email) is freeloading. The somewhat broken "solution" is charging a small fixed fee to the initiator. But this doesn't work in systems we would like to keep at zero cost because it's a blanket response to an acute problem - most coms are welcome and legitimate. Giving the callee the power to charge the caller a small "handling charge" if they don't like being bothered makes a lot of sense. Of course it has its own modes of abuse, but the best way to avoid that is not to send to people you don't know.