function performCheck()
{
 var bol = 1, msg;
 var email = document.getElementById( "newsletter" ).value;

 var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
 if (!filter.test( email ))
 {
  bol = 0;
  msg = "Adresa de email invalida!";
  alert( msg );
  return false;
 }
 else
 {	
  submitform('form_newsletter');
  return true;
 };
}