PHP Email, Obfuscate, Avoid Spambot

function comman_obfuscate($string)
{
    $encoded_string = '';
    for ($a = 0,$b = strlen($string);$a < $b;$a++)
    {
        $encoded_string .= '&#'.(mt_rand(0,1) == 0 ? 'x'.dechex(ord($string[$a])) : ord($string[$a]));
    }
    return $encoded_string;
}