Despite efforts to stem the billions of spam e-mails flooding inboxes, unwanted messages are still turning e-mail into a quagmire of misery. Spammers send out tens of millions of e-mails to unsuspecting computer users every day, employing a myriad of methods to ensure their pills, loans and "requests for our lord" pleas fox e-mail filters.
Some are even turning to prose and poetry to fool the technological safeguards people put in place. But a group of researchers at Microsoft think they may have come up with a solution that could, at least, slow down and deter the spammers.
The development has been called the Penny Black project, because it works on the idea that revolutionised the British postage system in the 1830s - that senders of mail should have to pay for it, not whoever is on the receiving end.
The payment is not made in the currency of money, but in the memory and the computer power required to work out cryptographic puzzles. As a result of this extra investment, spamming would become less profitable because costs would skyrocket in order to send as many e-mails.
All this clever puzzle-solving is done without the recipient of the e-mail being affected The idea was originally formulated to use CPU memory cycles by team member Cynthia Dwork in 1992. But they soon realised it was better to use memory latency - the time it takes for the computer's processor to get information from its memory chip - than CPU power.
Spam accounts for more than half of e-mails sent That way, it does not matter how old or new a computer is because the system does not rely on processor chip speeds, which can improve at rapid rates.
A cryptographic puzzle that is simple enough not to bog down the processor too much, but that requires information to be accessed from memory, levels the difference between older and newer computers.

MSR is in talks with various people to put the system into a useful anti-spam product.