People love their email. But over 40 percent of it is junk or spam, advertising sexual aids, porn, small-cap stocks, and fake Rolexes, and tempting the gullible with offers to share millions of
illicit Nigerian dollars, and so on. Almost 13 billion spam emails are sent every day, and
the traffic is increasing steadily.
A surge in the last few months may be due to the increasing use of "bot-nets." Some fear that spam will kill email.
What happens if you email the spammers to demand they stop? They're delighted! Now they know you read your spam, and they will send you more. They will also sell your email address to other spammers.
That's if your message gets through. Usually it won't, for they close their email accounts as soon as they have dumped a million or so spams into the Net, or the return box gets filled so quickly with complaints that it overflows, or the return address is fictitious.
Anti-spam laws have been passed in many countries. In 2003, the US Congress passed the Can-Spam Act to require that spammers provide working return addresses and ways for consumers to say, "Lay off!" Unfortunately, the spammers have already found ways around the law (for instance, by sending spams from or through computer systems outside the US). The
Federal Trade Commission is interested in the problem but has so far accomplished relatively little. Only a few cases have so far reached the courts. In May 2005, the
Massachusetts Attorney General filed a lawsuit against one of the world's biggest spam gangs, and an emergency court order demanded that the gang's web sites shut down.
In September 2006, "The Court of Appeals of Virginia upheld ... what is believed to be the first conviction in the nation under a state anti-spamming law that makes it a felony to send unsolicited mass e-mails."
Individual victims of spam have been inventive in devising ways to fight back.
Scam-baiters have had a great deal of fun with that Nigerian scam, for instance. Andrew Conry-Murray ("Fighting the Spam Monster--and Winning,"
Network Magazine, April 2003) describes a number of ways that computer scientists are developing to fight spam. They include blocking email from known spam sources (such as AOL), even at the risk of blocking legitimate email; accepting email only from trusted sources; filtering out email containing key words; and others, all of which can be circumvented by ingenious spammers. Fortunately, one new anti-spam technology, Bayesian filtering, in a way learns as it goes, adjusting to the spammers' attempts to get around blocks. However, once again the spammers are innovative alternatives, such as making their messages
images, not words (see "A Picture Is Worth Even More Spam,"
Communications of the ACM, October 2006).
Another technique, described in Evan I. Schwartz, "Spam Wars,"
Technology Review, July-August 2003, involves imposing costs on email. The basic idea is that of postage, but not enough for an ordinary user to notice. Consider that if you had to pay a tenth of a cent for every email you sent, you might spend a few dollars a year. But a spammer who sent a million spams a day would be out $365,000 a year. If that is not enough to slow the flow, raise the rate to a penny. Or instead of money, use time: Engineer the system so no one can send more than ten email messages per minute. Ordinary users would rarely notice, but the spammer's million daily emails would take over two months to send!
In February 2006,
AOL proposed charging commercial emailers for mail sent to AOL customers. This "certified email" scheme was
not well received, but both
AOL and Yahoo are pushing forward.
Another new technique proposes using peer-to-peer (P2P) networks to expand any one email recipient's database of identified spam. This technique has not yet been implemented, but its inventors propose to do so soon. A similar system was in the
alpha stage in 2004.
Still another technique would require authentication of senders or their domain names. Hardware-based solutions are also being tried, but
PC World said in June 2006 that they were only partially effective.
A more promising tack may lie in taking a more biological approach. Living things such as our own bodies have an immune system that, in essence, defines what belongs in the body and attacks what does not. It can go wrong, but in general it works quite well. Researchers have recognized that a similar approach might work well in computers as a defense again viruses, worms, trojans, and spyware, if not spam, at least since 1997 (see Stephanie Forrest,
et al., "Computer Immunology,"
Communications of the ACM, October 1997). A few researchers have been working on the problem, with some signs of progress recently. See, for instance, Li Tao, "An Immune Based Dynamic Intrusion Detection Model,"
Chinese Science Bulletin (November 2005).
As we have seen before, with translation and surveillance, for instance, we often identify an emerging technology or a cluster of related technologies by naming the problem they address. Here the problem is spam or other unwanted email. The previous paragraphs mention several technologies that may prove useful, but some have other applications as well. P2P, for instance, is used most notoriously in file-sharing and music-downloading. Some applications are legal. Some are not. Some have already been thought of. Some have not.
