htmlpurifier/library/HTMLPurifier/URIScheme/mailto.php

<?php

// VERY RELAXED! Shouldn't cause problems, not even Firefox checks if the
// email is valid, but be careful!

/**
 * Validates mailto (for E-mail) according to RFC 2368
 * @todo Validate the email address
 * @todo Filter allowed query parameters
 */

class HTMLPurifier_URIScheme_mailto extends HTMLPurifier_URIScheme {
    
    public $browsable = false;
    
    public function validate(&$uri, $config, $context) {
        parent::validate($uri, $config, $context);
        $uri->userinfo = null;
        $uri->host     = null;
        $uri->port     = null;
        // we need to validate path against RFC 2368's addr-spec
        return true;
    }
    
}