Preparing and Pre-Empting
You need a couple things before you can really take effective action against SPAM. Your email software must be capable of filtering incoming email. All of the major email applications (such as Eudora, Outlook, and Pegasus) support filtering. We will use multiple email addresses to allow us to filter out SPAM and identify the source - you can't combat SPAM effectively without them.
 

You need to use a website hosting provider that allows unlimited email aliases or addresses, and/or a catch-all email address. An "alias" is an email address that forwards to some other address (for example, webmaster@domain.com forwarding to your real email address). A "catch-all" email address will forward any emails sent to unknown addresses in your domain. I just use the catch-all, so that every message goes to my real email address. If you have more than a one-person operation, however, multiple accounts and aliases are pretty much a necessity.

Fighting Back
The first step in fighting back against the spammers is understanding where they get your email address. You must diligently protect your email address, if you ever hope to stop them. Once your email address gets into the wrong hands, it will be sold on CD-ROM (via junk mail, of course) to thousands of spammers. Once that happens, you've lost the fight.

Spam Source #1: Domain Name Registrations
When you register a domain name, you must provide a contact email address. If you give them your real email address, you've just given it to everyone, including the spammers. Instead, use a portable email address (like Hotmail) to set up your domain. If you have multiple domains, you can also use an alias (domains@yourdomain.com) on your primary domain for all registrations. With an alias, you can use your email software to filter out and save any emails that come to that address from your registrar's domain.

Spam Source #2: Web Forms & Email Newsletters
If you give your real email address on any web form, or use it to subscribe to an email newsletter, you are asking for trouble. Instead, create a unique email address for each website or newsletter. I just use the website's domain name for this. For example, if you subscribe to SiteProNews as "sitepronews.com@yourdomain.com" and let your catch-all address route it to you, you will always know where the email came from. If that address ever starts receiving junk mail, you can filter it out using your email software. If you submit to search engines or free-for-all links pages (FFA's), use a unique email address.

Spam Source #3: Your Website
The biggest source of email addresses used by spammers is your website. Most websites list multiple contact addresses, etc. Any time an email address appears on your website in plain text, even if it's hidden in a JavaScript or form field, you're opening yourself up to having that email address captured.

The Big Battle: Securing Your Website From Spambots
Almost every website operator wants search engine spiders to visit. After all, search engines are the best source of free traffic on the web. In the event that you don't want them to visit, they are easily kept at bay with a properly formatted "robots.txt" file.

Unfortunately, there's another group of spiders out there crawling the web, with an entirely different purpose. These are the spiders that visit site after site, collecting email addresses. You may know them as spambots, email harvesters, or any number of unpublishable names.

When it comes to controlling these rogue spiders, a robots.txt file simply won't get the job done. In fact, most spam robots ignore robots.txt. That doesn't mean you have to give up, and just let them have their way. The following techniques will stop these spiders in their tracks.

Technique #1: Use JavaScript To Mask Email Addresses
One of the weaknesses that spiders of all kinds suffer from is an inability to process scripts. Adding a small snippet of JavaScript in place of an email address effectively renders the address invisible to spiders, while leaving it accessible to your visitors with all but the most primitive web browsers.

In the three examples below, simply substitute your username (the first half of your email address, everything before the @ symbol) and your hostname (everything after the @ symbol). To use the scripts, just insert them into your page's HTML wherever you need them to be displayed.

Example 1: Creating A Spam-Proof Mailto Link
This snippet of JavaScript code creates a clickable link that launches the visitor's email application, assuming that their system is configured to work with "mailto:" hyperlinks. You can replace the link text with your own message, but see example 2 if you want to display your email address as the link text.

<script language=javascript>
<!--
var username = "username";
var hostname = "yourdomain.com";
var linktext = "Click Here To Send Me Email";
document.write("<a href=" + "mail" + "to:" + username +
"@" + hostname + ">" + linktext + "</a>")
//-->
</script>

Example 2: A Spam-Proof Mailto Link With Your Email Address Showing
Some visitors won't be able to use a mailto link. This snippet shows your email address in the link so they can copy and paste, or type it by hand:

<script language=javascript>
<!--
var username = "username";
var hostname = "yourdomain.com";
var linktext = username + "@" + hostname;
document.write("<a href=" + "mail" + "to:" + username +
"@" + hostname + ">" + linktext + "</a>")
//-->
</script>

Example 3: Display Your Email Address Without A Mailto Link
Here's a snippet that displays your email address a clickable link:

<script language=javascript>
<!--
var username = "username";
var hostname = "yourdomain.com";
var linktext = username + "@" + hostname;
document.write(username + "@" + hostname)
//-->
</script>

About The Author
Dan Thies has been helping his clients (and friends) promote their websites since 1996. His latest book, Search Engine Optimization Fast Start , offers a simple, step by step plan to increase your website's search engine traffic.