$('newsletter-validate-detail').onsubmit = function(){
var emailRegEx = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
str =$('newsletter').value;
  if(str.match(emailRegEx)){
      $('newsletter-validate-detail').submit();
    }else{
      alert('Please enter a valid email address.');
    return false;
  }
}
$('newsletter-validate-detail-footer').onsubmit = function(){
var emailRegEx = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
str =$('newsletter-footer').value;
  if(str.match(emailRegEx)){
      $('newsletter-validate-detail-footer').submit();
    }else{
      alert('Please enter a valid email address.');
    return false;
  }
}