How to Avoid Spambots

How to Avoid Being Harvested by Spambots

Complete Obfuscation

All of these steps to mung your email address and prevent it from falling into the hands of spammers can, unfortunately, be successfully interpreted by some of the most advanced harvesters in use today. While studies in the last year still show that the advanced munging techniques described on the previous page will stop at least 85% of the current crop of harvesters, as spambots inevitably improve these techniques will become less effective.

There are, however, at least two techniques which appear not only to currently be 100% successful at protecting email addresses, but are likely to remain so for some time. The first technique uses Javascript to obscure the address, the second hides the email address in an image. Harvesters are unlikely to begin interpreting Javascript any time soon and even less likely to do the OCR required to pull an email address from an image.

The text field below is a tool to create your own Javascript email address obscuring script. Enter your email address in the box and press the "OBSCURE!" button. You can then copy the resulting script and place it anywhere on your webpages where you want your email address to appear.

Here is what an email address created with this technique looks like when included on your website:

Assuming you have Javascript enabled in your browser, the email address should look like a normal, clickable email address. View the source of this page to see how it is obscured through the Javascript.

The second technique involves hiding your email address in an image. You can use any popular graphics program to encode your email address as a GIF, PNG, JPEG, or other standard web format. Because the current crop of spambots is not able to interpret the contents of images email addresses displayed on a website in this way are likely to remain protected.

It should be noted that both of these techniques are likely to remain sound for some time to come. Harvesters that interpret the Javascript on every page they encounter would face a substantial risk of getting stuck in infinite loops or crashing due to malformed Javascript. A spambot that can do OCR is even less likely. Not only would such a harvester need to download images, creating a significantly higher bandwidth load than spammers currently face, but it would then need to process every one of those images. This is likely beyond the current computing power of a legitimate company like Google; there is virtually no risk spambots will develop this capability in the foreseeable future.

That is not to say these techniques are not without drawbacks. The first technique may hide your address from visitors to your site who have Javascript disabled. To solve this, you can combine the two techniques into a hybrid as follows:

Those two lines, if replaced with your custom code and image, will display a clickable link to visitors with Javascript enabled and will display a non-harvestable image of an email address to those who do not.

You should be aware that this solution, while very reliable, does still have at least one downside. Visually impaired visitors to your site may not be able to access your email addresses. Many screen readers do not support Javascript and therefore the image will be displayed — which, obviously, isn't of any good if you can't see it. Users of text-based web browsers, such as Lynx, will also be unable to see your addresses. For this reason, it's always advisable to include, where possible, a "contact us" form or other alternative means for visitors to get in touch with you.

On the following pages we'll discuss some ways to stop harvesters from visiting your pages altogether, making steps like obfuscation and munging less necessary.