I saw an interesting article on Yahoo! the other day. It appears that someone at Carnegie Mellon came up with the idea to use a CAPTCHA script to mask e-mail addresses. Basically, they provide you with special link code to put in place of your normal mailto link. You can use the link anyway you want, but the script generates some HTML code automatically that looks similar to:
user<a href="http://mailhide.recaptcha.net/d?k=01quxf658CWzRNQC34kj75Ug==&c=5Sc_I7orZzXLkOX6E7fontrPSKXj6NS2QC0a-5mV5Gk=" onclick="window.open('http://mailhide.recaptcha.net/d?k=01quxf658CWzRNQC34kj75Ug==&c=5Sc_I7orZzXLkOX6E7fontrPSKXj6NS2QC0a-5mV5Gk=', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false;" title="Reveal this e-mail address">...</a>@example.com
In the example above, the whole e-mail address would actually be email@example.com, but the rest of the username is obscured by the script. Of course, they also supply you with just the address to the CAPTCHA page, so that you can build your own link any way you want.
The link, in turn, leads to a page with a CAPTCHA script. Once you correctly answer the CAPTCHA question, you’re lead to another page with the complete e-mail address. The script is called Mailhide, and it appears to be a completely free utility. It’s such a simple idea that I can’t believe no one thought of this before.