function validateForm(f){
with(f){
var foundAt=email.value.indexOf("@");

if(vorname.value==""){
alert("Please enter your first name.");
vorname.focus();
return false;
}
if(name.value==""){
alert("Please enter your surname");
name.focus();
return false;
}
if(foundAt<1){
alert("Please enter a valid email adress.");
email.focus();
return false;
}
if(nachricht.value==""){
alert("Please enter your message.");
nachricht.focus();
return false;
}
}
}