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