Other than the canned meat sold by Hormel, the term spam is used to describe unsolicited bulk email. It is rumored that the term Spam came from an old Monty Python comedy sketch about a restaurant where every item on the menu came with an order of Spam. Certainly this is an accurate comparison due to the ubiquitous nature of junk email, which first started to appear in bulk in the early 1990s. The usual definition of spam is email that is unsolicited, without prior permission or business relationship, transmitted in mass mailings and containing commercial content.

As the Internet became used increasingly in homes and businesses, marketers did their best to promote their wares through this new medium. Email, unlike postal mail that requires a separate postage charge, can be sent out in bulk just as cheaply as it can be sent to one person. Therefor, bulk email became an irresistible way to advertise for Internet-based marketers. Their only difficulty was to find valid email addresses for recipients.

Bulk marketers began to compile lists of known email addresses and sell them to other advertisers. Consumers often sign up on mailing lists to be notified of sales or product promotions, even from companies the openly pass their clients' email addresses on to other companies. Spammers get email addresses off publicly available web sites and user groups. Spammers have even been known to hack into businesses' customer databases to harvest even more addresses for their lists.

It did not matter if some of the addresses had expired; if an address is not valid, email is simply not delivered. Millions of simultaneous email messages could be sent out at little or no cost to the marketer, so customer targeting was no longer necessary. Spam was lucrative for marketers, as any response rate at all would bring in profit from this essentially free advertising.

Much of the spam advertised goods and services of dubious quality, such as pornography, get-rich-quick schemes, multilevel marketing, stock promotions, quack health remedies, and of course the services of internet marketers offering to send out even more spam on behalf of the email account holder.

Internet users, however, were less pleased with spam than were internet merchants. Many consumers resented receiving advertisements through what is to be considered a personal electronic mailbox. Finding legitimate emails became a time consuming process of sifting through hundreds of unwanted messages. Furthermore, some of the spam contained viruses. Constant flow of spam used up bandwidth and filled up server space. Parents objected to pornographic pictures being sent to family websites which were accessed by children.

Spam is costly to the business world. It takes up bandwidth and server storage space. Legitimate email may be lost, inboxes fill up and staff spend office time deleting unwanted email. A study published in May 2004 by Radicati Group shows that large businesses (with approximately 10,000 employees) which do not use spam filters lose $2,923.20 per user per year or a total of $30 million annually in terms of email productivity. As Bill Gates said, "The torrent of unwanted, unsolicited, often offensive and sometimes fraudulent email is eroding trust in technology, costing business billions of dollars a year, and decreasing our collective ability to realize technologys full potential.

Aside from being an annoying, time-wasting nuisance, spam also includes "phishing" emails, false requests purportedly from companies such as Ebay or Paypal, asking for credit card information.

The total savings for businesses which do install anti-spam filters is approximately $19.9 million per year. (Claburn, 2004). Filtering software looks for tell-tale signs such as an invalid or spoofed "From" address, invalid host name in the From or To address, similarity to previous emails, direct SMTP transmission from a host without a fixed IP address, receipt of the email from an unrestricted mail server, an IP address, netblock or domain matching that of a known spammer or spamhaus, and unique headers created by spamming software.

No matter what kind of anti-spam system you employ in your home or office, from the most basic to the most thorough, it's bound to save you time and money.