diff --git a/src/Symfony/Component/Mailer/Transport.php b/src/Symfony/Component/Mailer/Transport.php
index 45dfc8b9ba..d72f1fa39e 100644
--- a/src/Symfony/Component/Mailer/Transport.php
+++ b/src/Symfony/Component/Mailer/Transport.php
@@ -149,7 +149,7 @@ class Transport
         throw new UnsupportedSchemeException($dsn);
     }
 
-    private static function getDefaultFactories(EventDispatcherInterface $dispatcher = null, HttpClientInterface $client = null, LoggerInterface $logger = null): iterable
+    public static function getDefaultFactories(EventDispatcherInterface $dispatcher = null, HttpClientInterface $client = null, LoggerInterface $logger = null): iterable
     {
         foreach (self::FACTORY_CLASSES as $factoryClass) {
             if (class_exists($factoryClass)) {