1. Create a droplet with a name like "Lastform".
2. Put this code into the droplet :


if(!isset($_SESSION['lastform'])) return 'No data';
$value = $_SESSION['lastform'];
unset($_SESSION['lastform']);
return $value;



3. On your "Thank you" page you now can put [[lastform]] somewhere. 
This will show the content of the email that has been sent to the website owner.