diff --git a/DependencyInjection/FrameworkExtension.php b/DependencyInjection/FrameworkExtension.php
index f918eafbb..1c5725335 100644
--- a/DependencyInjection/FrameworkExtension.php
+++ b/DependencyInjection/FrameworkExtension.php
@@ -2282,13 +2282,17 @@ private function registerMessengerConfiguration(array $config, ContainerBuilder
         $transportRateLimiterReferences = [];
         foreach ($config['transports'] as $name => $transport) {
             $serializerId = $transport['serializer'] ?? 'messenger.default_serializer';
+            $tags = [
+                'alias' => $name,
+                'is_failure_transport' => \in_array($name, $failureTransports),
+            ];
+            if (str_starts_with($transport['dsn'], 'sync://')) {
+                $tags['is_consumable'] = false;
+            }
             $transportDefinition = (new Definition(TransportInterface::class))
                 ->setFactory([new Reference('messenger.transport_factory'), 'createTransport'])
                 ->setArguments([$transport['dsn'], $transport['options'] + ['transport_name' => $name], new Reference($serializerId)])
-                ->addTag('messenger.receiver', [
-                    'alias' => $name,
-                    'is_failure_transport' => \in_array($name, $failureTransports),
-                ])
+                ->addTag('messenger.receiver', $tags)
             ;
             $container->setDefinition($transportId = 'messenger.transport.'.$name, $transportDefinition);
             $senderAliases[$name] = $transportId;
@@ -2660,7 +2664,6 @@ private function registerMailerConfiguration(array $config, ContainerBuilder $co
         }
         $transports = $config['dsn'] ? ['main' => $config['dsn']] : $config['transports'];
         $container->getDefinition('mailer.transports')->setArgument(0, $transports);
-        $container->getDefinition('mailer.default_transport')->setArgument(0, current($transports));
 
         $mailer = $container->getDefinition('mailer.mailer');
         if (false === $messageBus = $config['message_bus']) {
diff --git a/Resources/config/mailer.php b/Resources/config/mailer.php
index 9eb545ca2..7a3a95739 100644
--- a/Resources/config/mailer.php
+++ b/Resources/config/mailer.php
@@ -46,10 +46,7 @@
             ])
 
         ->set('mailer.default_transport', TransportInterface::class)
-            ->factory([service('mailer.transport_factory'), 'fromString'])
-            ->args([
-                abstract_arg('env(MAILER_DSN)'),
-            ])
+        ->alias('mailer.default_transport', 'mailer.transports')
         ->alias(TransportInterface::class, 'mailer.default_transport')
 
         ->set('mailer.messenger.message_handler', MessageHandler::class)
diff --git a/Tests/DependencyInjection/FrameworkExtensionTestCase.php b/Tests/DependencyInjection/FrameworkExtensionTestCase.php
index c891ec143..7f94b83ce 100644
--- a/Tests/DependencyInjection/FrameworkExtensionTestCase.php
+++ b/Tests/DependencyInjection/FrameworkExtensionTestCase.php
@@ -2103,8 +2103,7 @@ public function testMailer(string $configFile, array $expectedTransports, array
         $this->assertTrue($container->hasAlias('mailer'));
         $this->assertTrue($container->hasDefinition('mailer.transports'));
         $this->assertSame($expectedTransports, $container->getDefinition('mailer.transports')->getArgument(0));
-        $this->assertTrue($container->hasDefinition('mailer.default_transport'));
-        $this->assertSame(current($expectedTransports), $container->getDefinition('mailer.default_transport')->getArgument(0));
+        $this->assertTrue($container->hasAlias('mailer.default_transport'));
         $this->assertTrue($container->hasDefinition('mailer.envelope_listener'));
         $l = $container->getDefinition('mailer.envelope_listener');
         $this->assertSame('sender@example.org', $l->getArgument(0));