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Chapter 4; Protecting Email Addresses

Spammers use various techniques to collect or harvest email addresses. The main methods are described in this chapter.

Websites
Many small organizations now have websites and provide an email address for customers to contact them. A simple HTML link of the form mailto:user@domain.com is easy to implement (all popular HTML editors allow you to create this), and the results are easy to retrieve—they arrive in the user's mailbox.

The alternative to a mailto: link in a web page is to have a web form where the customer enters an email address and a message, and then submits the form. The data is processed by the web server and forwarded to the recipient. This is less flexible than an email—for example, attachments cannot be added. Additionally, the web form relies on the customer to enter their email address correctly. If this is typed incorrectly, then the customer contact will be lost.

From an early time in the history of the Internet, automated computer programs have tried to download web pages and follow links to other web pages. Typically, these spiders walk the Web to generate indexes for search engines such as Google and AltaVista. This technique has been adopted by spammers to capture email addresses. It is currently the most common method for harvesting email addresses.

Once a spammer's spider has discovered a company website, the email addresses listed on it will start to receive spam. Organizations can carry on using the mailto: links, or they can implement other methods to capture customer input, such as a web form. These other options may incur additional expense.

Two techniques can be used in simple web pages to render an email address invisible to a spammer's web spider and yet allow a user to click on the link. These are described in the following sections.