Add built-in protocols (smtp, sendmail) + the new one (native)

Author: l-vo

mailer.rst

@@ -27,15 +27,64 @@ over SMTP by configuring the DSN in your ``.env`` file (the ``user``,
     # .env
     MAILER_DSN=smtp://user:[email protected]:port
 
+.. configuration-block::
+
+    .. code-block:: yaml
+
+        # config/packages/mailer.yaml
+        framework:
+            mailer:
+                dsn: '%env(MAILER_DSN)%'
+
+    .. code-block:: xml
+
+        <!-- config/packages/mailer.xml -->
+        <?xml version="1.0" encoding="UTF-8" ?>
+        <container xmlns="http://symfony.com/schema/dic/services"
+            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+            xmlns:framework="http://symfony.com/schema/dic/symfony"
+            xsi:schemaLocation="http://symfony.com/schema/dic/services
+                https://symfony.com/schema/dic/services/services-1.0.xsd
+                http://symfony.com/schema/dic/symfony https://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
+
+            <framework:config>
+                <framework:mailer dsn="%env(MAILER_DSN)%"/>
+            </framework:config>
+        </container>
+
+    .. code-block:: php
+
+        // config/packages/mailer.php
+        use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+
+        return static function (ContainerConfigurator $containerConfigurator): void {
+            $containerConfigurator->extension('framework', [
+                'mailer' => [
+                    'dsn' => '%env(MAILER_DSN)%',
+                ]
+            ]);
+        };
+
 .. caution::
 
     If you are migrating from Swiftmailer (and the Swiftmailer bundle), be
     warned that the DSN format is different.
 
+Using built-in transports
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+============ ==================================== ===========
+DSN protocol Example                              Description
+============ ==================================== ===========
+smtp         smtp://user:[email protected]:25 Mailer uses an SMTP server to send emails
+sendmail     sendmail://default                   Mailer uses the local sendmail binary (`/usr/sbin/sendmail` with `-bs` options) to send emails
+native       native://default                     Mailer uses the sendmail binary and options configured in the `sendmail_path` setting of `php.ini`. On Windows hosts, Mailer fallbacks to `smtp` and `smtp_port` `php.ini` settings when `sendmail_path` is not configured.
+============ ==================================== ===========
+
 Using a 3rd Party Transport
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Instead of using your own SMTP server, you can send emails via a 3rd party
+Instead of using your own SMTP server or sendmail binary, you can send emails via a 3rd party
 provider. Mailer supports several - install whichever you want:
 
 ==================  ==============================================
@@ -902,6 +951,8 @@ and it will select the appropriate certificate depending on the ``To`` option::
     $firstEncryptedEmail = $encrypter->encrypt($firstEmail);
     $secondEncryptedEmail = $encrypter->encrypt($secondEmail);
 
+.. _multiple-email-transports:
+
 Multiple Email Transports
 -------------------------