According to Project Honey Pot, a voluntary community of web defenders, formed by web administrators as an alliance against online fraud and abuse in 2004, it takes the average spammer around two and a half weeks from harvesting an email address to sending the first spam message to this address. Every time a user's email address is harvested from a website, it results in an average of 850 spam messages.

Spammers use dozens of tricks to get through email filters that block messages containing frequently used spam words. Monday is the busiest day of the week for email spam, and Saturday the quietest.

The networking computer company Cisco estimated that worldwide spam volumes this year could rise by 30 to 40 per cent compared with 2009. Spammers already send out up to 100 million junk emails a day and, although the vast majority are never opened, enough people click on the links to make spam a multimillion-dollar industry.