function nametest() {
  if (document.Bestellformular.Name.value== "") {
    alert("Please insert your last name");
    return false;} 
    else {vornametest();}
}

 function vornametest() {
  if (document.Bestellformular.Vorname.value== "") {
    alert("Please insert your first name");
    return false;} 
    else {strassetest();}
}

function strassetest() {
 
  if (document.Bestellformular.Strasse.value== "") {
    alert("Please enter the street");
return false;} 
   
    else {PLZtest();}
   
}

function PLZtest() {
 
  if (document.Bestellformular.PLZ_Ort.value== "") {
    alert("Please enter the ZIP-Code and the city");
    return false;}
    else {telefontest();}
   
}

function telefontest() {
 
  if (document.Bestellformular.Telefon.value== "") {
    alert("Please enter the phone number");
    return false;}
    else {mailtest();}
}

function mailtest() {
 
  if ((document.Bestellformular.Email.value== "")||(document.Bestellformular.Email.value.indexOf('@', 0) == -1)){
    alert("Please enter a valid email adress");
    return false;}
    else {
    
    document.Bestellformular.submit();
}
}