public function sendEmail(OrderEvent $event)
    {
        $order = $event->getOrder();

        // Be sure that we have a document to download
        $virtualProductCount = OrderProductQuery::create()
            ->filterByOrderId($order->getId())
            ->filterByVirtual(true)
            ->filterByVirtualDocument(null, Criteria::NOT_EQUAL)
            ->count();

        if ($virtualProductCount > 0) {
            $customer = $order->getCustomer();

            $this->mailer->sendEmailToCustomer(
                'mail_virtualproduct',
                $customer,
                [
                    'customer_id' => $customer->getId(),
                    'order_id' => $order->getId(),
                    'order_ref' => $order->getRef(),
                    'order_date' => $order->getCreatedAt(),
                    'update_date' => $order->getUpdatedAt()
                ]
            );
        } else {
            Tlog::getInstance()->warning(
                "Virtual product download message not sent to customer: there's nothing to downnload"
            );
        }
    }