// JavaScript Document
function checkEmail(email){
filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if (filter.test(email)) {
  // Yay! valid
	document.getElementById('newsletterSubmit').disabled = false;
}
else
  document.getElementById('newsletterSubmit').disabled = "disabled";
}