diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
index 8a149e25515e5..0d1c6acf11860 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
@@ -1556,6 +1556,7 @@ private function addMailerSection(ArrayNodeDefinition $rootNode)
                     ->{!class_exists(FullStack::class) && class_exists(Mailer::class) ? 'canBeDisabled' : 'canBeEnabled'}()
                     ->children()
                         ->scalarNode('dsn')->defaultValue('smtp://null')->end()
+                        ->booleanNode('async')->defaultValue(false)->end()
                         ->arrayNode('envelope')
                             ->info('Mailer Envelope configuration')
                             ->children()
diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
index 7ed04a5bb15b7..ae37a98c020b4 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
@@ -1952,6 +1952,8 @@ private function registerMailerConfiguration(array $config, ContainerBuilder $co
         }
 
         $loader->load('mailer.xml');
+
+        $container->getDefinition('mailer.mailer')->setArgument(2, $config['async']);
         $container->getDefinition('mailer.default_transport')->setArgument(0, $config['dsn']);
 
         $recipients = $config['envelope']['recipients'] ?? null;
diff --git a/src/Symfony/Component/Mailer/Mailer.php b/src/Symfony/Component/Mailer/Mailer.php
index 324f50cad7803..034f534417a60 100644
--- a/src/Symfony/Component/Mailer/Mailer.php
+++ b/src/Symfony/Component/Mailer/Mailer.php
@@ -23,16 +23,22 @@ class Mailer implements MailerInterface
 {
     private $transport;
     private $bus;
+    private $async;
 
-    public function __construct(TransportInterface $transport, MessageBusInterface $bus = null)
+    public function __construct(TransportInterface $transport, MessageBusInterface $bus = null, bool $async = false)
     {
+        if ($async && null === $bus) {
+            throw new \LogicException('You cannot send messages asynchronously as the Symfony Messenger Component is not installed. Try running "composer require symfony/messenger".');
+        }
+
         $this->transport = $transport;
         $this->bus = $bus;
+        $this->async = $async;
     }
 
     public function send(RawMessage $message, SmtpEnvelope $envelope = null): void
     {
-        if (null === $this->bus) {
+        if (!$this->async) {
             $this->transport->send($message, $envelope);
 
             return;