Mailto is a free, open source class written by Debugged Interactive Designs in PHP4 to obfuscate e-mail addresses from spam harvesters. The class lets you easily encode an entire anchor tag using ROT13 Encryption. At run-time, javascript is used to decode the ROT13 encryption. If javascript is disabled, then the e-mail address is safely shown by reversing the e-mail address using PHP and re-reversing (versing?) it at run-time using CSS.