try new mailboxcheck

zimbraAddressCheck.php

@@ -11,7 +11,7 @@ require_once(ROOTDIR . '/includes/dbfunctions.php');
 require_once dirname(__FILE__) . '/zimbraSingle.inc';
 
 $whmcs = App::self();
-$whmcs->assign('id', $_GET['pid']);
+$whmcs->set_req_var('id', $_GET['pid']);
 if(zimbraSingleDoesEMailExist($_GET['name'], $_GET['domain'])) {
 	echo 'no';
 } else {