diff --git a/src/Symfony/Component/Mailer/Transport/AbstractTransport.php b/src/Symfony/Component/Mailer/Transport/AbstractTransport.php
index 7ee4513190b33..31dddaa63ace3 100644
--- a/src/Symfony/Component/Mailer/Transport/AbstractTransport.php
+++ b/src/Symfony/Component/Mailer/Transport/AbstractTransport.php
@@ -61,6 +61,7 @@ public function send(RawMessage $message, Envelope $envelope = null): ?SentMessa
             $event = new MessageEvent($message, $envelope, (string) $this);
             $this->dispatcher->dispatch($event);
             $envelope = $event->getEnvelope();
+            $message = $event->getMessage();
         }
 
         $message = new SentMessage($message, $envelope);