function isNotValidEmail(elem)
{
	return (!elem.value.match(/^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/));
}
function isEmpty(elem)
{
	return elem.value.length == 0;
}
function validate(form)
{
	document.getElementById("errormessage").innerText="";
	form.newsletterfirstname.className = null;
	form.newsletterlastname.className = null;
	form.newsletteremail.className = null;
}
function invalidate(msgText,element)
{
	document.getElementById("errormessage").innerText=msgText;
	element.className = "invalidInput";
	element.focus(); 
}
function validateNewsletter(form)
{
	validate(form);
	if(isEmpty(form.newsletterfirstname))
	{
		invalidate("first name cannot be empty",form.newsletterfirstname);
		return false;
	}
	if(isEmpty(form.newsletterlastname))
	{
		invalidate("last name cannot be empty",form.newsletterlastname);
		return false;
	}
	if(isNotValidEmail(form.newsletteremail))
	{
		invalidate("invalid email address",form.newsletteremail);
		return false;
	}
	form.postback.value = form.id;
	return true;
}