Email javascript validation - JavaScript Snipplr Social Repository

function checkMail(email){
	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (filter.test(email)) {
		return true;
	}
	return false;
}