diff --git a/src/Symfony/Component/Mailer/Tests/Transport/Smtp/SmtpTransportTest.php b/src/Symfony/Component/Mailer/Tests/Transport/Smtp/SmtpTransportTest.php
index 38229ce844..91b1685077 100644
--- a/src/Symfony/Component/Mailer/Tests/Transport/Smtp/SmtpTransportTest.php
+++ b/src/Symfony/Component/Mailer/Tests/Transport/Smtp/SmtpTransportTest.php
@@ -18,6 +18,8 @@ use Symfony\Component\Mailer\Transport\Smtp\SmtpTransport;
 use Symfony\Component\Mailer\Transport\Smtp\Stream\AbstractStream;
 use Symfony\Component\Mailer\Transport\Smtp\Stream\SocketStream;
 use Symfony\Component\Mime\Address;
+use Symfony\Component\Mime\Email;
+use Symfony\Component\Mime\Exception\InvalidArgumentException;
 use Symfony\Component\Mime\RawMessage;
 
 class SmtpTransportTest extends TestCase
@@ -86,6 +88,29 @@ class SmtpTransportTest extends TestCase
         $transport->send(new RawMessage('Message 3'), $envelope);
         $this->assertContains("NOOP\r\n", $stream->getCommands());
     }
+
+    public function testSendInvalidMessage()
+    {
+        $stream = new DummyStream();
+
+        $transport = new SmtpTransport($stream);
+        $transport->setPingThreshold(1);
+
+        $message = new Email();
+        $message->to('recipient@example.org');
+        $message->from('sender@example.org');
+        $message->attachFromPath('/does_not_exists');
+
+        try {
+            $transport->send($message);
+            $this->fail('Expected Symfony\Component\Mime\Exception\InvalidArgumentException to be thrown');
+        } catch (InvalidArgumentException $e) {
+            $this->assertMatchesRegularExpression('{Path "/does_not_exists"}i', $e->getMessage());
+        }
+
+        $this->assertNotContains("\r\n.\r\n", $stream->getCommands());
+        $this->assertTrue($stream->isClosed());
+    }
 }
 
 class DummyStream extends AbstractStream
@@ -164,4 +189,10 @@ class DummyStream extends AbstractStream
     {
         return $this->closed;
     }
+
+    public function terminate(): void
+    {
+        parent::terminate();
+        $this->closed = true;
+    }
 }
diff --git a/src/Symfony/Component/Mailer/Transport/Smtp/SmtpTransport.php b/src/Symfony/Component/Mailer/Transport/Smtp/SmtpTransport.php
index 5ef8a88255..9e5ead35a3 100644
--- a/src/Symfony/Component/Mailer/Transport/Smtp/SmtpTransport.php
+++ b/src/Symfony/Component/Mailer/Transport/Smtp/SmtpTransport.php
@@ -159,7 +159,7 @@ class SmtpTransport extends AbstractTransport
             return $name;
         }
 
-        return sprintf('smtp://sendmail');
+        return 'smtp://sendmail';
     }
 
     /**
@@ -200,10 +200,19 @@ class SmtpTransport extends AbstractTransport
             }
 
             $this->executeCommand("DATA\r\n", [354]);
-            foreach (AbstractStream::replace("\r\n.", "\r\n..", $message->toIterable()) as $chunk) {
-                $this->stream->write($chunk, false);
+            try {
+                foreach (AbstractStream::replace("\r\n.", "\r\n..", $message->toIterable()) as $chunk) {
+                    $this->stream->write($chunk, false);
+                }
+                $this->stream->flush();
+            } catch (TransportExceptionInterface $e) {
+                throw $e;
+            } catch (\Exception $e) {
+                $this->stream->terminate();
+                $this->started = false;
+                $this->getLogger()->debug(sprintf('Email transport "%s" stopped', __CLASS__));
+                throw $e;
             }
-            $this->stream->flush();
             $this->executeCommand("\r\n.\r\n", [250]);
             $message->appendDebug($this->stream->getDebug());
             $this->lastMessageTime = microtime(true);