minor #17586 Add a note about using Gmail vs an Email catcher (fabpot)

This PR was merged into the 5.4 branch.

Discussion
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Add a note about using Gmail vs an Email catcher

We have many people complaining about the difficulty to set up Gmail. But we should recommend not using it as this is not a good way to send emails from an application. I've also added a note about using an email catcher as I think this is the way to go in development (and automatically configured nowadays via our Docker integration).

Commits
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0cae5b8 Add a note about using Gmail vs an Email catcher

Author: javiereguiluz

mailer.rst

@@ -12,7 +12,6 @@ integration, CSS inlining, file attachments and a lot more. Get them installed w
 
     $ composer require symfony/mailer
 
-
 .. _mailer-transport-setup:
 
 Transport Setup
@@ -105,14 +104,13 @@ native        ``native://default``                      Mailer uses the sendmail
 Using a 3rd Party Transport
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-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:
+Instead of using your own SMTP server or sendmail binary, you can send emails
+via a 3rd party provider:
 
 ==================  ==============================================
 Service             Install with
 ==================  ==============================================
 Amazon SES          ``composer require symfony/amazon-mailer``
-Gmail               ``composer require symfony/google-mailer``
 MailChimp           ``composer require symfony/mailchimp-mailer``
 Mailgun             ``composer require symfony/mailgun-mailer``
 Mailjet             ``composer require symfony/mailjet-mailer``
@@ -122,6 +120,14 @@ Sendinblue          ``composer require symfony/sendinblue-mailer``
 OhMySMTP            ``composer require symfony/oh-my-smtp-mailer``
 ==================  ==============================================
 
+.. note::
+
+    As a convenience, Symfony also provides support for Gmail (``composer
+    require symfony/google-mailer``), but this should not be used in
+    production. In development, you should probably use an :ref:`email catcher
+    <mail-catcher>` instead. Note that most supported providers also provide a
+    free tier.
+
 .. versionadded:: 5.2
 
     The Sendinblue integration was introduced in Symfony 5.2.
@@ -1404,6 +1410,17 @@ is sent::
 Development & Debugging
 -----------------------
 
+.. _mail-catcher:
+
+Enabling an Email Catcher
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When developing locally, it is recommended to use an email catcher. If you have
+enabled Docker support via Symfony recipes, an email catcher is automatically
+configured. In addition, if you are using the :doc:`Symfony local web server
+</setup/symfony_server>`, the mailer DSN is automatically exposed via the
+:ref:`symfony binary Docker integration <symfony-server-docker>`.
+
 Disabling Delivery
 ~~~~~~~~~~~~~~~~~~