bug #30787 [Mailer] Fix SMTP support when a message cannot be sent (f…

…abpot)

This PR was merged into the 4.3-dev branch.

Discussion
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[Mailer] Fix SMTP support when a message cannot be sent

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | yes
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

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Commits
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3d25c1c [Mailer] fixed SMTP support when a message cannot be sent

src/Symfony/Component/Mailer/Transport/Smtp/SmtpTransport.php

@@ -111,7 +111,13 @@ public function send(RawMessage $message, SmtpEnvelope $envelope = null): ?SentM
             $this->start();
         }
 
-        $message = parent::send($message, $envelope);
+        try {
+            $message = parent::send($message, $envelope);
+        } catch (TransportExceptionInterface $e) {
+            $this->executeCommand("RSET\r\n", [250]);
+
+            throw $e;
+        }
 
         $this->checkRestartThreshold();