useSandbox(); $verified = $ipn->verifyIPN(); if ($verified) { /* * Process IPN * A list of variables is available here: * https://developer.paypal.com/webapps/developer/docs/classic/ipn/integration-guide/IPNandPDTVariables/ */ } // Reply with an empty 200 response to indicate to paypal the IPN was received correctly. header("HTTP/1.1 200 OK");