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