diff --git a/app/code/Magento/Sales/Model/Order/Email/Sender/OrderSender.php b/app/code/Magento/Sales/Model/Order/Email/Sender/OrderSender.php
index 2944b8ccef647..92d00d0436634 100644
--- a/app/code/Magento/Sales/Model/Order/Email/Sender/OrderSender.php
+++ b/app/code/Magento/Sales/Model/Order/Email/Sender/OrderSender.php
@@ -131,14 +131,17 @@ protected function prepareTemplate(Order $order)
             'formattedShippingAddress' => $this->getFormattedShippingAddress($order),
             'formattedBillingAddress' => $this->getFormattedBillingAddress($order),
         ];
-        $transport = new DataObject($transport);
+        $transportObject = new DataObject($transport);
 
+        /**
+         * Event argument `transport` is @deprecated. Use `transportObject` instead.
+         */
         $this->eventManager->dispatch(
             'email_order_set_template_vars_before',
-            ['sender' => $this, 'transport' => $transport]
+            ['sender' => $this, 'transport' => $transportObject->getData(), 'transportObject' => $transportObject]
         );
 
-        $this->templateContainer->setTemplateVars($transport->getData());
+        $this->templateContainer->setTemplateVars($transportObject->getData());
 
         parent::prepareTemplate($order);
     }