function validate(form) {
  if (form.address.value == "") {
    alert("Geben Sie bitte Ihre E-Mail Adresse ein.");
    form.address.focus();
    return false;
    }
    
  if (form.address.value.indexOf('@') == -1) {
    alert("Geben Sie bitte eine gültige E-Mail Adresse ein.");
    form.address.focus();
    return false;
    }
    
  if ((form.address.value.indexOf('.', form.address.value.indexOf('@'))) < (form.address.value.indexOf('@') + 2)) {
    alert("Geben Sie bitte eine gültige E-Mail Adresse ein.");
    form.address.focus();
    return false;
    }
    
  if ((form.message.value == "") || (form.message.value == "text verfassen ...")) {
    alert("Geben Sie bitte Ihre Nachricht ein.");
    form.message.focus();
    return false;
    }
  return true;
  }
  
function NewWindow(mypage, myname, w, h, scroll) {
  var winl = (screen.width - w) / 2;
  var wint = (screen.height - h) / 2;
  winprops = 'height='+h+',width='+w+',top='+wint+',left='+winl+',scrollbars='+scroll+',resizable'
  win = window.open(mypage, myname, winprops)
  if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}

function checkField(field, content) {
  if (field.value == "") {
    field.value = content;
  }
  else if (field.value == content) {
    field.value = "";  
  }
}