function checkEmail(emailaddress) {
	var filter = /^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.([a-z]){2,4})$/;
	if (!filter.test(emailaddress)) {
		return false;
	}
	return true;
}