not necessarily. Even in my prototype sender pays email environment (camram/2 penny blue), the cost of the stamp was pushed on the message originator i.e. the e

not necessarily. Even in my prototype sender pays email environment (camram/2 penny blue), the cost of the stamp was pushed on the message originator i.e. the email client. The mail server delivering the mail to another server on the Internet doesn't need to take that message if it doesn't have postage. There are a few other ideas the project explored including using captive zombie nets generating postage for a company's email using spare cycles on desktops. Truth be told, whole distributed postage stamp generating model looked a hell of a lot like bitcoin mining.