Spammers use automated systems to harvest e-mail addresses from your web pages. Using the same technology as web indexing services like Google and Yahoo, spammers use programs to read the source from your web pages and look for e-mail addresses. They save these and sell them to one another by the millions. It takes just few hours to harvest a couple of million e-mail addresses.

SpamStop works by doing something very simple. It presents the viewer with a random image like you see below and ask that the viwer read the word and type it back. The image is jumbled on purpose in order to prevent Optical Character Recognition software from being used. The technogy to read text like this does not yet exist. This stops spammers dead in their tracks. Their software can't get past this page.

The technology behind SpamStop is called CAPTCHA (short for Completely Automated Public Turing test to tell Computers and Humans Apart). You can read more about it in the November 2003 edition of Scientific American. Similar systems have been employed by Yahoo and Hotmail.

That's how SpamStop works. It's very simple, yet tremendously effective. Go ahead, try it yourself. Type the word you see below and type in in the field provided.