function sprawdzPola()
{
  var theMessage = "Proszę uzupełnić dane: \n-----------------------------------\n";
  var noErrors = theMessage;

  var email_1 = document.getElementById('biu_mail').value;  
  var filterMail  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
    
  if( !filterMail.test(email_1) || email_1 == '' ){
    theMessage = theMessage + "\n --> adres mail";
  }
  
  
  if (theMessage == noErrors) {
    return true;
  } else {
    alert(theMessage);
    return false;
  }
}