Bill Gates talked about this idea at Davos as one of the plansk to eliminate spam in the next coupel years. Yahoo too is considering it. NYTimes discusses the idea in more detail:
Ten days ago, Bill Gates, Microsoft’s chairman, told the World Economic Forum in Davos, Switzerland, that spam would not be a problem in two years, in part because of systems that would require people to pay money to send e-mail. Yahoo, meanwhile, is quietly evaluating an e-mail postage plan being developed by Goodmail, a Silicon Valley start-up company.
“The fundamental problem with spam is there is not enough friction in sending e-mail,” said Brad Garlinghouse, Yahoo’s manager for communications products.
Goodmail, founded by Daniel T. Dreymann, an Israeli entrepreneur, is developing a system that it hopes will be easier to adopt. It proposes that only high-volume mailers pay postage at first, at a rate of a penny a message, with the money going to the e-mail recipient’s Internet access provider. (The company suggests, but does not require, that the Internet providers share the payments with their users, either through rebates or by lowering monthly fees.)
The Goodmail system is designed to work even if not all senders and not all Internet providers participate. A mass e-mailer would sign up with Goodmail, buying a block of stamps – actually an encrypted code number – that it would insert in the header of each e-mail message. If the Internet provider of the recipient participates in the system, it decrypts the stamp and submits it to Goodmail. Only then is the sender’s account charged a penny and the receiving I.S.P. paid the penny, minus a service fee by Goodmail for acting as a clearinghouse.
Senders do not pay for stamps that are not used, but they do pay whether an e-mail recipient reads the message or not.
Under this plan, Internet providers would still accept incoming e-mail without stamps. But that mail would be subject to the same sort of spam filters in use now, which can at times divert legitimate mail. The Internet providers would deliver all stamped mail without any filter. Goodmail does not require that stamped mail be requested by the recipient, the so-called opt-in requirement of most other anti-spam systems.
I hope that if this comes through, they will look at purchasing power parity before fixing the rates. A penny in the US is worth 45 paise in India in the existing dollar exchange and about 7 paise in the context of PPP.