Spam fighters have come up with an idea to frustrate the automatic creation of email accounts often used to send spam.

Researchers at Carnegie Mellon University have designed software which acts as a gatekeeper, blocking computerised creation of accounts with Web mail services.

The idea is to use a form of Turing Test to distinguish humans for Web robots, called captchas (completely automated public Turing tests to tell computers and humans apart).

Gimpy, one on these captchas, selects a word from a dictionary and mangles its image in a way that is obvious to humans to interpret but confuses a machine.

Yahoo! began using Gimpy last year to block bots from creating email accounts. This month, Hotmail plans to introduce a similar system, according to wire reports.

The idea is far from foolproof. Computers could be programmed to try multiple different phrases or spammers could hire people to manually create accounts. Also the idea does nothing to stop spammers harvesting email account details from the Net in the first place.

Still the idea is intriguing and could serve to deter spammers from using Hotmail and the like. Which would be nice. ®