WordPress.org

Let's say you have in your site a link as <a class="stylish-class" href="no.spam@spam.com" title="c'mon mail me!" target="_blank">mail me</a>.

It is obfuscated while WordPress is building the page, using WordPress hook system. Everybody (real browsers, spam harvesters and spam crawlers) will receive an obfuscated string: <span id="hkmuob-id-2709" class="hkmuob_noscript">mail me (no<span class="HkMuob_display"> NULL</span>.spam<span class="HkMuob_display"> null</span>@<span class="HkMuob_display">null </span>spam<span class="HkMuob_display"> NULL</span>.com)</span>, which is pretty much unreadable and looks like anything but a link.

For users without JavaScript or that simply don't wanna enable it on your site, thanks to CSS they'll see in the screen a text like "mail me (no.spam@spam.com)". It's not clickable, and Copy & Paste doesn't work properly, but it is readable and they can understand what you meant and see the original email/URL.

But, when users have JavaScript enabled (more than 90% of our real visitors), thet will see the obfuscated link exactally as it was originally, a clickable link with all its original attributes, the tooltip title and _blank behavior!