Those who forget history are doomed to repeat it.

For example: say you're an entertainment executive looking to stop some incredibly popular kind of online information transmission – infringing music copyright, say. Where would you look to find a rich history of this kind of online battle? Why, the Spam Wars, of course. Where else?

Electronic spam has existed in one form or another since 1978. For 30 years, networks have served as battlefield in the fight between those who want your mailbox filled with their adverts and those who want to help you avoid the come-ons.

The war against spam has been a dismal failure: there's far more spam today than ever before, and it grows more sinister by the day. Gary Thuerk's 1978 bulk email advertisement for a new Digital Equipment model (widely held to be the first spam) was merely annoying and gormless. Today, the spam you receive might hijack your computer, turning it into a spyware-riddled zombie that harvests your banking details and passwords and uses its idle resources to send out even more spam. It might encrypt your files and demand anonymous cash transfers before unlocking them. It might be a front for a Spanish Prisoner scammer who will rob you of every cent you and your loved ones have.

And (practically) everyone hates spam. It's not like copyrighted music, where millions of time-rich, cash-poor teenagers and cheapskates are willing to spend their days and nights figuring out how to get more of it in their lives. In the Spam War, the message recipients are enthusiastic supporters of the cause.

Let's have a look at some of the spam war tactics that have been tried and have been found wanting.

Content-based filters

These were pretty effective for a very brief period, but the spammers quickly outmanoeuvred them. The invention of word-salads (randomly cut/pasted statistically normal text harvested from the net), alphabetical substitutions, and other tricksy techniques have trumped the idea that you can fight spam just by prohibiting certain words, phrases or media.

Unintended consequence: It's practically impossible to have an email conversation about Viagra, inheritances, medical conditions related to genitals, and a host of other subjects because of all the "helpful" filters still fighting last year's spam battle, diligently vaporising anyone who uses the forbidden words.

Blacklisting

Anti-spam groups maintain blacklists of "rogue" internet service providers and their IPs – the numbers that identify individual computers. These are ISPs that, due to negligence, malice, error, or a difference of opinion on how to best block bad actors, end up emitting a lot of spam to the rest of the internet. Again, this worked pretty well for a short period, but was quickly overwhelmed by more sophisticated spammers who switched from running rogue email servers to simply hijacking end users' PCs and using them to send spams from millions of IPs.

Unintended consequence: IP blocking becomes a form of collective punishment in which innocent people are punished (blocked from part or all of the internet) because one person did something naughty, and none of the punished had the power to prevent it. A single IP can stand in for thousands or even millions of users.

The blacklists are maintained by groups whose identity is shrouded in secrecy ("to prevent retaliation from criminal spam syndicates") and operate at Star Chambers who convict their targets in secrecy, without the right of appeal or the ability to confront your accuser. Allegations abound that blacklisters have targeted their critics and stuck them in the black holes merely for criticising them, and not because of any spam.

Blocking open servers

Email servers used to to be set up to accept and deliver mail for anyone: all you needed to do to send an email was to contact any known email server and ask it to forward your message for you. This made email sending incredibly easy to set up and run – if your local mailserver croaked, you could just switch to another one. But these servers were

also juicy targets for spammers who abused their hospitality to send millions of spams. A combination of blacklisting and social pressure have all but killed the open server in the wild. Unintended consequence: It's infinitely harder to send legitimate email, as anyone who has ever logged into a hotel or institutional network and discovered that you can't reach your mailserver any more can attest. And still the spam rolls in: legitimate users lack the motivation and capacity to learn to send mail in a block-ridden environment, whereas spammers have the motivation and capacity in spades.

There have been other failures in the field, and a few successes (my daily spam influx dropped from more than 20,000 to a few hundred when my sysadmin switched on something called greylisting). But these three failures are particularly instructive because they represent the main strategic objectives of the entertainment industry's copyright enforcement plans.

Every legislative and normative proposal recapitulates the worst mistakes of the spamfight: from Viacom's demand that Google automatically detect copyright-infringing videos while they're being uploaded; to the three-accusations-and-you're-offline proposal from the BPI; to the notion in the G8's Anti-Counterfeiting Trade Agreement of turning copyright holders into judge, jury and executioner for what content can travel online and who can see it.

The Spam Wars have shown us that great intentions and powerful weapons can have terrible outcomes – outcomes where the innocent are inconvenienced and the guilty merely evolve into more resistant, more deadly organisms.