A CAPTCHA is a test intended to be easy to the average human reader but difficult for automated process to answer correctly. An easy and effective way to protect an individual email address is using the mailhide feature from reCAPTCHA.

HTML Encoding

There are always "spam bots" or "email harvesters" crawling the Internet. They browse every page they can and grab every email address they can. They add the collected addresses to a list or database that is then used by spammers. There are many techniques to protect your address. The most common is to write it in a strange form, such as myname SPAMFREE AT domain DOT com. Intelligent bots are now learning tricks to read even these kinds of addresses. Also, addresses of this format must also be interpreted by a human and cannot form mailto links.

There is another, less common way to protect your address, and few (if any) spam bots are programmed to detect it. You can encode your email address and mailto link using HTML entities. You can, in fact, also combine this with other techniques! When you encode the address using HTML entities, it appears normally in a browser (and therefore to a human), but a bot will only get a series of senseless characters. For example, when you encode the project name:

...into HTML entities, you get:

...which continues to appear as:

This is a live example!

There are several ways to encode your address like this. I have provided an online tool to do this quickly and easily at:

Download My Encoder

I have provided the source code for my encoder page. It is written in PHP. I have also provided a GPG signature. Key ID: 0x299407D8

License: Public Domain

This script works on PHP 4 or 5 with register_globals off and renders HTML 4.01 Strict. It could use some improvement. Maybe someday I'll rewrite it in Python. :-)