Webservice : add order without mail notification

[Sterk]

Hi all,

I am trying to create order without email notification to admin.

Order is created successfully

so i use this :

 $opt = array('resource' => 'orders');
            $opt['postXml'] = $xml->asXML(); 
            $xml = $webService->add($opt);
            $id_order = $xml->order->id;

but i recieve an "new order" email to admin@email

How can i create a order with api without sending email ?

I have tried this but whithout success :  $opt = array('resource' => 'orders?sendemail=0');

Thanks for any help