diff --git a/src/Symfony/Component/Mailer/EventListener/EnvelopeListener.php b/src/Symfony/Component/Mailer/EventListener/EnvelopeListener.php
index b439b2f0bf41..b2980bc5cf6b 100644
--- a/src/Symfony/Component/Mailer/EventListener/EnvelopeListener.php
+++ b/src/Symfony/Component/Mailer/EventListener/EnvelopeListener.php
@@ -48,7 +48,7 @@ public function onMessage(MessageEvent $event): void
             $message = $event->getMessage();
             if ($message instanceof Message) {
                 if (!$message->getHeaders()->has('Sender') && !$message->getHeaders()->has('From')) {
-                    $message->getHeaders()->addMailboxHeader('Sender', $this->sender->getAddress());
+                    $message->getHeaders()->addMailboxHeader('Sender', $this->sender);
                 }
             }
         }