Yahoo looks to penny per email to stop spam

Yahoo researchers are looking to charity to cut down on spam.

Currently in private beta, Yahoo's CentMail sells 500 email stamps for five dollars.

Each time you send an email, you use a penny stamp code, which lets the system know it's legitimate, as no spammer could afford to stamp each and every of the million and millions of emails they send.

Previous systems have tried similar ideas, but CentMail is different as the cash goes to charity. "We think this is a more socially efficient approach to reducing spam," Yahoo researcher Sharad Goel told the New Scientist.

Spam currently makes up as much as 90 per cent of all email sent, making it an expensive and time consuming issue.