openpolitics.com

Spam Filtering through Email Guarantees

Technical approaches to spam such as authentication and bayesian analysis are useful in the short term, but ultimately an economic solution is needed.

I propose guaranteed email: email whose sender offers to pay if the recipient is unhappy with the message.

Others have proposed electronic postage as a way to price the junk out of the market. That's essentially what I propose except

1. no money changes hands if the recipient is happy with the message.
2. money is paid to the recipient, rather than a third party like the postal service or Microsoft

Example

I write an email to Dave Winer. Dave gets a lot of email and I want my message to stand out from the spam and other unsolicited "great ideas".

If I were sending Dave a letter, I would be willing to pay the postal service 37 cents; but to make my email stand out I offer 67 cents. Economists call this signaling.

My email client attaches a file to my email and names it guarantee.xml. This file follows a standard format

    <guarantee type> 
            satisfaction guaranteed
            noncommercial
            existing business relationship
            family
            not pornography
        </guarantee type>
    <guarantee amount>
        $0.05
        $0.25
        $0.67
        $1.25
        $7.50</guarantee amount>
    <signature url>http://www.example.com/signature/?username=timlangeman 
    </signature url>
    <signature contents>
      Standard PGP signature used to verify: 
        the guarantee is offered by the sendor,
        applies to the recipient, 
        for the content of the email, 
        with the guarantee type and amount
    </signature contents>

Dave's email client already has filtering software built-in. It would take extra programming, but this filtering software could be modified to parse the guarantee.xml file, lookup and verify the signature, and factor-in the guarantee amount.

To increase Dave's trust that I won't default on the 67 cents, my Credit Card (or some such) agency signs my key in a similar way that I signed the email, asserting that they will back up any email guarantee, for up to (say) $7.50.

"Cashing" unwanted Email

If Dave "cashes" his email, my Credit card company will bill me. If I don't pay my bills, they will revoke their signature on my key.

Since there are a smaller number of Credit agencies, Dave's filtering software can set up a "trusted" set up Guarantors. (This key signing is similar to the way SSL Certificates work).

Email Clients

Ideally every email program will have a button to "cash" an email. Barring that, people could forward the email on to an address to receive payment. Microsoft's Outlook and Hotmail are the biggest email clients. Plugins to these would go a long way in gaining momentum.

Credit Companies

As for the "Credit Companies", this is the most difficult part of this whole proposal. It's going to take a company with experience dealing with fraud and billing, who is also willing to deal in small transactions. I think Paypal might be a good fit. They're not a conventional bank and it would be a great way to add customers.

The upside of this is that they could charge a small percentage for every "cashed" email. That's gotta be worth something.

Related

• ZDNet Discussion: skeptical of any scheme proposed by Bill Gates that involves collecting money
• FogCreek Discussion with similar idea, found after this piece was written
• Vadim Makarov with the same idea, also found after this piece was written
• Bonded Sender
• How to Stop Junk E-Mail: Charge for the Stamp