Php: Mask email address in string, using preg_replace_callback

hs_mailreplace.php

<?php

function hs_mailreplace($str) {

    return preg_replace_callback ('^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})^',
        create_function (
            '$str',
            'for ($i = 0; $i < strlen($str[0]); $i++) {
                $result .= "&#" . ord(substr($str[0], $i, 1)) . ";";
            };
            return $result;'
        ), 
    $str);

}

?>

create_function() is now deprecated.