Spam celebrated its 30th birthday last month and it's doubtful that anyone that ever owned an email address is singing its praises. In May 1978, 393 employees of Arpanet received the first ever spam email in history from another company called Digital Equipment Corporation (DEC) advertising their new computer systems.

Arpanet, a predecessor of the internet, was used by the U.S. Air Force for security research and intended for official government business only. So these unsolicited bulk commercial ads were seen as a blatant violation of the use of Arpanet and it was determined that appropriate action would be taken to prevent its occurrence ever again. That was then… and obviously more wishful thinking than fact.

Thirty years later, sending billions of unwanted emails every day, spammers are trying to sell everything from Viagra to alopecia and weight loss treatments or anything else that might obtain money or personal data from users through deception. The word Spam once only referred to a strange form of meat in a can, but the term was later applied to junk email, referencing a comedy skit from Monty Python's Flying Circus, where all meals in a restaurant come with spam, spam and more spam. Junk email has since become the principal meaning of the word spam. Plentiful but not quite so tasty.

The number of spam emails has grown steadily over the past five years and according to recent data, over 92 percent of all e-mails sent in the first three months of 2008 could be classified as spam. Google, for example, has found that users of its email service, Gmail, receive four times more spam today than they did 2004 and the over all trend is only expected to continue upward.

The methods used by companies to send spam have changed a lot in the last three decades. Thirty years ago the senders of spam email had to type in each address by hand, while today powerful software programs known as botnets perform this task at amazing speed, sending out billions of unsolicited emails a day. But spam took a new step in its evolution in 2005 with the use of images such as GIFs and JPEGs which can easily escape anti-spam programs developed to sort through the text content of an e-mail message.

Spammers have continued to find ingenious ways to circumvent the spam filters, including the use of Word documents and other complex file types such as PowerPoint, PDF and zip files. Compressing the spam into ZIP files renders the e-mail unreadable by security gateways and other spam prevention software because a zip file can only be read once it is decompressed, or unzipped.

On of the more recent trends being used by spammers to get the message through is with the use of the MP3 format. The audio files are actually disguised as music by top musicians, which is usually just enough bait to get most people to open them. Stock spammers in particular have been using this method to convince the email recipient to invest in some obscure stock. Again as with most attachments anti-spam filters do not handle attachments very well because they can’t analyze the attachment content.

So why do spammers put so much time and effort into designing such complex files, complete with images and even audio, if the spam can simple be passed through as a text file? While money is always the initial motivation there is apparently the challenge of beating the anti-spam establishment. Spammers admit that spam filters make their job more difficult but at the same time they take pride in the fact that they have never come across a spam filter that they couldn’t get around.

Anti-spam technology has made some great advances in the last few years, but stamping out spam has proved far more difficult than originally imagined. Spam filters can give users a sense of false confidence. They can do their job very well but at the same time that can catch some important documents and for a business this can mean considerable financial loss.

As long as a faction of spam recipients not only open these emails but actually purchase product or service or fall for the various scams involved, spam will continue to flourish. But an educated internet consumer can go a long way in helping to quell that growth.