I have find a solution to my problem by changing my expression to this:
<pre lang="xml"><script type="text/javascript">
jQuery(function(){
jQuery("#email").validate({
expression: "if (VAL.match(/^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$/)) return true; else return false;",
message: "<br>Please provide a valid email address!!</b>"
});
});
</script>