[FrameworkBundle] Add mailer monolog channel on mailer transport definitions

src/Symfony/Bundle/FrameworkBundle/Resources/config/mailer_transports.php

@@ -34,6 +34,7 @@ return static function (ContainerConfigurator $container) {
                 service('http_client')->ignoreOnInvalid(),
                 service('logger')->ignoreOnInvalid(),
             ])
+            ->tag('monolog.logger', ['channel' => 'mailer'])
 
         ->set('mailer.transport_factory.amazon', SesTransportFactory::class)
             ->parent('mailer.transport_factory.abstract')

src/Symfony/Component/Mailer/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+5.3.0
+-----
+
+ * added the `mailer` monolog channel and set it on all transport definitions
+
 5.2.0
 -----