Microsoft Wants Spammers to Pay a Price

Microsoft Corp., which has declared war on unsolicited electronic mail, is aiming to raise the cost of spam for senders with a new technology.

It costs virtually the same to send one message as it does 1 million. In a research project called Penny Black, the software maker is looking at ways to make it difficult for spammers to spread offers for get-rich-quick schemes, porn and penis enlargement products.

“The general idea is to force the sender of an e-mail to incur some kind of cost,” said Cynthia Dwork, a researcher at Microsoft.

The codename Penny Black is derived from an 1830s stamp used in Britain that reversed the cost of postage to the sender, rather than the original method of charging the letter recipient.

Similarly, an e-mail sender’s computer would be required to spend about 10 seconds solving a complex math problem and attaching proof of the effort to a message, Dwork said.

For most users sending a few to several dozen e-mails daily, that doesn’t amount to much computation time. Spammers who send millions of messages, however, would have to buy racks of computers.

Making spammers pay is not a new concept. A similar model being considered is the “challenge-response” scenario whereby an e-mail recipient would require the sender to answer a question in order to accept a message.

Redmond, Wash.-based Microsoft also is aiming to raise the cost of sending mass e-mail in other ways. It is suing e-mail marketers in New York and Washington for sending e-mail with allegedly false information that clogs up its networks.

Spam’s burden on networks, resources and lost productivity amounted to more than $10 billion in 2003, according to consulting firm Ferris Research.