Why do we get so much spam?

More than half of us have our email address available in the public domain - a fact which offers some insight into why we receive so much unsolicited email.

In total, 55 per cent of respondents to a silicon.com survey admitted to having their email address readily available to the public on the web - whether on a personal website or a company site.

Coupled with the fact that 60 per cent of respondents admitted to replying to spam emails, the survey reveals two of the main reasons why we are inundated with unwanted email offers, of everything from unclaimed Nigerian fortunes to generic Viagra and miracle weight loss pills.

But one is obviously far more avoidable than the other. By making email addresses available online, users are increasing their exposure to spam. Software favoured by spammers can crawl the web harvesting email addresses, but many companies, who rely on the web to advertise their services and contact details, have accepted this side effect of accessibility.

However, end-user education - particularly with regards to the practice of responding to spam - forms an important third tier in the fight against spam.

Alyn Hockey, director of research at email filtering specialist Clearswift, said: "Spam is now the biggest reason why people are knocking on our door."

"There are three levels on which to fight spam. Obviously technology is the most important. The technological solution is probably going to catch most spam," he said, but pointed at the need for a legal deterrent and better end-user education.

"We also need legislation - in part to enable us to take action when spammers are caught. But thirdly, we need better end user education.

"One of the best things a company can do is to teach staff how to use email more efficiently - teaching them everything from email etiquette and managing their inbox to how they should deal with spam."

The danger with individuals responding to spam is that it becomes self-perpetuating. The more emails users reply to the more times they confirm their email address as live and the more spam they receive.

Hockey believes it's time companies add end-user education to their anti-spam approach in order to break that cycle.