remove deprecated email utils and email_backend configs

airflow-core/docs/howto/email-config.rst

@@ -25,15 +25,13 @@ in the ``[email]`` section.
 .. code-block:: ini
 
   [email]
-  email_backend = airflow.utils.email.send_email_smtp
   subject_template = /path/to/my_subject_template_file
   html_content_template = /path/to/my_html_content_template_file
 
 Equivalent environment variables look like:
 
 .. code-block:: sh
 
-  AIRFLOW__EMAIL__EMAIL_BACKEND=airflow.utils.email.send_email_smtp
   AIRFLOW__EMAIL__SUBJECT_TEMPLATE=/path/to/my_subject_template_file
   AIRFLOW__EMAIL__HTML_CONTENT_TEMPLATE=/path/to/my_html_content_template_file
 
@@ -57,14 +55,6 @@ connection called ``smtp_default`` of ``Email`` type, or choose a custom connect
 the configuration & store SMTP username-password in it. Other SMTP settings like host, port etc always gets picked up
 from the configuration only. The connection can be of any type (for example 'HTTP connection').
 
-If you want to check which email backend is currently set, you can use ``airflow config get-value email email_backend`` command as in
-the example below.
-
-.. code-block:: bash
-
-    $ airflow config get-value email email_backend
-    airflow.utils.email.send_email_smtp
-
 To access the task's information you use `Jinja Templating <http://jinja.pocoo.org/docs/dev/>`_  in your template files.
 
 For example a ``html_content_template`` file could look like this:

airflow-core/src/airflow/cli/commands/config_command.py

@@ -818,12 +818,6 @@ def message(self) -> str | None:
         config=ConfigParameter("triggerer", "default_capacity"),
         renamed_to=ConfigParameter("triggerer", "capacity"),
     ),
-    # email
-    ConfigChange(
-        config=ConfigParameter("email", "email_backend"),
-        was_removed=True,
-        remove_if_equals="airflow.contrib.utils.sendgrid.send_email",
-    ),
     # elasticsearch
     ConfigChange(
         config=ConfigParameter("elasticsearch", "log_id_template"),

airflow-core/src/airflow/config_templates/config.yml

@@ -2192,6 +2192,10 @@ email:
     email_backend:
       description: Email backend to use
       version_added: ~
+      version_deprecated: 3.2.0
+      deprecation_reason: |
+        Since the legacy email_on_failure and email_on_retry attributes are replaced with SmtpNotifier
+        from apache-airflow-providers-smtp, email_backend is no longer used.
       type: string
       example: ~
       default: "airflow.utils.email.send_email_smtp"

airflow-ctl/src/airflowctl/ctl/commands/config_command.py

@@ -700,12 +700,6 @@ def _get_option_value(self, config_resp: Config) -> str | None:
         renamed_to=ConfigParameter("triggerer", "capacity"),
         breaking=True,
     ),
-    # email
-    ConfigChange(
-        config=ConfigParameter("email", "email_backend"),
-        was_removed=True,
-        remove_if_equals="airflow.contrib.utils.sendgrid.send_email",
-    ),
     # elasticsearch
     ConfigChange(
         config=ConfigParameter("elasticsearch", "log_id_template"),