function ShortValidator(form) { 
var x = form.email.value;
var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9])+$/;

if (filter.test(x) == false) {
  	alert('Please enter a valid email address.');
 	form.email.focus();
  	return false;
}

form.Submit.disabled = true; 
return true; 
}