Fixed #36894 -- Added TypeError for conflicting arguments in mail APIs.

A TypeError is now raised if fail_silently=True, auth_user, or auth_password
are provided along a connection.

Updated AdminEmailHandler in django.utils.log to remove redundant
fail_silently=True.

Thanks Mike Edmunds for the report and Jacob Tyler Walls for the review.

7 files changed, 177 insertions, 9 deletions

diff --git a/AUTHORS b/AUTHORS
index c480402993..9379176a4c 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -865,6 +865,7 @@ answer newbie questions, and generally made Django that much better:
     plisk
     polpak@yahoo.com
     pradeep.gowda@gmail.com
+    Praful Gulani <https://github.com/prafulgulani>
     Prashant Pandey <https://prashantpandey9.in>
     Preston Holmes <preston@ptone.com>
     Preston Timmons <prestontimmons@gmail.com>
diff --git a/django/core/mail/__init__.py b/django/core/mail/__init__.py
index 4d7f8bf1d9..6a0baa48ed 100644
--- a/django/core/mail/__init__.py
+++ b/django/core/mail/__init__.py
@@ -94,6 +94,17 @@ def send_mail(
     Note: The API for this method is frozen. New code wanting to extend the
     functionality should use the EmailMessage class directly.
     """
+    if connection is not None:
+        if fail_silently:
+            raise TypeError(
+                "fail_silently cannot be used with a connection. "
+                "Pass fail_silently to get_connection() instead."
+            )
+        if auth_user is not None or auth_password is not None:
+            raise TypeError(
+                "auth_user and auth_password cannot be used with a connection. "
+                "Pass auth_user and auth_password to get_connection() instead."
+            )
     connection = connection or get_connection(
         username=auth_user,
         password=auth_password,
@@ -137,6 +148,17 @@ def send_mass_mail(
     Note: The API for this method is frozen. New code wanting to extend the
     functionality should use the EmailMessage class directly.
     """
+    if connection is not None:
+        if fail_silently:
+            raise TypeError(
+                "fail_silently cannot be used with a connection. "
+                "Pass fail_silently to get_connection() instead."
+            )
+        if auth_user is not None or auth_password is not None:
+            raise TypeError(
+                "auth_user and auth_password cannot be used with a connection. "
+                "Pass auth_user and auth_password to get_connection() instead."
+            )
     connection = connection or get_connection(
         username=auth_user,
         password=auth_password,
@@ -158,6 +180,11 @@ def _send_server_message(
     fail_silently=False,
     connection=None,
 ):
+    if connection is not None and fail_silently:
+        raise TypeError(
+            "fail_silently cannot be used with a connection. "
+            "Pass fail_silently to get_connection() instead."
+        )
     recipients = getattr(settings, setting_name)
     if not recipients:
         return
diff --git a/django/core/mail/message.py b/django/core/mail/message.py
index 66d5efeb63..6eb85c6a2a 100644
--- a/django/core/mail/message.py
+++ b/django/core/mail/message.py
@@ -355,6 +355,13 @@ class EmailMessage:
             # Don't bother creating the network connection if there's nobody to
             # send to.
             return 0
+
+        if fail_silently and self.connection:
+            raise TypeError(
+                "fail_silently cannot be used with a connection. "
+                "Pass fail_silently to get_connection() instead."
+            )
+
         return self.get_connection(fail_silently).send_messages([self])
 
     def attach(self, filename=None, content=None, mimetype=None):
diff --git a/django/utils/log.py b/django/utils/log.py
index d4e96a9816..9a3a7d9f62 100644
--- a/django/utils/log.py
+++ b/django/utils/log.py
@@ -132,7 +132,7 @@ class AdminEmailHandler(logging.Handler):
             reporter.get_traceback_text(),
         )
         html_message = reporter.get_traceback_html() if self.include_html else None
-        self.send_mail(subject, message, fail_silently=True, html_message=html_message)
+        self.send_mail(subject, message, html_message=html_message)
 
     def send_mail(self, subject, message, *args, **kwargs):
         mail.mail_admins(
diff --git a/docs/releases/6.1.txt b/docs/releases/6.1.txt
index 67891c5bf7..6b18331a1b 100644
--- a/docs/releases/6.1.txt
+++ b/docs/releases/6.1.txt
@@ -457,6 +457,10 @@ short-term maintenance releases. Django 6.1 supports MariaDB 10.11 and higher.
 Miscellaneous
 -------------
 
+* Providing ``fail_silently=True``, ``auth_user``, or ``auth_password`` to mail
+  sending functions (such as :func:`~django.core.mail.send_mail`) while also
+  providing a ``connection`` now raises a ``TypeError``.
+
 * :class:`~django.contrib.contenttypes.fields.GenericForeignKey` now uses a
   separate descriptor class: the private ``GenericForeignKeyDescriptor``.
 
diff --git a/docs/topics/email.txt b/docs/topics/email.txt
index 6a32a0728e..c10aac2f80 100644
--- a/docs/topics/email.txt
+++ b/docs/topics/email.txt
@@ -120,6 +120,12 @@ can be ``0`` or ``1`` since it can only send one message).
     Passing ``fail_silently`` and later parameters as positional arguments is
     deprecated.
 
+.. versionchanged:: 6.1
+
+    Older versions ignored ``fail_silently=True``, ``auth_user``,
+    and ``auth_password`` when a ``connection`` was also provided.
+    This now raises a ``TypeError``.
+
 ``send_mass_mail()``
 ====================
 
@@ -164,6 +170,13 @@ The return value will be the number of successfully delivered messages.
     Passing ``fail_silently`` and later parameters as positional arguments is
     deprecated.
 
+
+.. versionchanged:: 6.1
+
+    Older versions ignored ``fail_silently=True``, ``auth_user``,
+    and ``auth_password`` when a ``connection`` was also provided.
+    This now raises a ``TypeError``.
+
 ``send_mass_mail()`` vs. ``send_mail()``
 ----------------------------------------
 
@@ -198,6 +211,11 @@ If ``html_message`` is provided, the resulting email will be a
     Passing ``fail_silently`` and later parameters as positional arguments is
     deprecated.
 
+.. versionchanged:: 6.1
+
+    Older versions ignored ``fail_silently=True`` when a ``connection``
+    was also provided. This now raises a ``TypeError``.
+
 ``mail_managers()``
 ===================
 
@@ -212,6 +230,11 @@ setting.
     Passing ``fail_silently`` and later parameters as positional arguments is
     deprecated.
 
+.. versionchanged:: 6.1
+
+    Older versions ignored ``fail_silently=True`` when a ``connection``
+    was also provided. This now raises a ``TypeError``.
+
 Examples
 ========
 
@@ -403,6 +426,11 @@ email backend API :ref:`provides an alternative
         an exception. It will return ``1`` if the message was sent
         successfully, otherwise ``0``.
 
+        .. versionchanged:: 6.1
+
+            Older versions ignored ``fail_silently=True`` when a ``connection``
+            was also provided. This now raises a ``TypeError``.
+
     .. method:: message(policy=email.policy.default)
 
         Constructs and returns a Python :class:`email.message.EmailMessage`
diff --git a/tests/mail/tests.py b/tests/mail/tests.py
index 851d1c371c..3ba3b9d062 100644
--- a/tests/mail/tests.py
+++ b/tests/mail/tests.py
@@ -1999,6 +1999,107 @@ class MailTests(MailTestsMixin, SimpleTestCase):
             message.as_string(policy=policy.compat32),
         )
 
+    def test_send_mail_fail_silently_conflict(self):
+        msg = (
+            "fail_silently cannot be used with a connection. "
+            "Pass fail_silently to get_connection() instead."
+        )
+        with self.assertRaisesMessage(TypeError, msg):
+            mail.send_mail(
+                "Subject",
+                "Body",
+                "from@example.com",
+                ["to@example.com"],
+                fail_silently=True,
+                connection=mail.get_connection(),
+            )
+
+    def test_send_mail_auth_conflict(self):
+        msg = (
+            "auth_user and auth_password cannot be used with a connection. "
+            "Pass auth_user and auth_password to get_connection() instead."
+        )
+        for param in ["auth_user", "auth_password"]:
+            with (
+                self.subTest(param=param),
+                self.assertRaisesMessage(TypeError, msg),
+            ):
+                mail.send_mail(
+                    "subject",
+                    "body",
+                    "from@example.com",
+                    ["to@example.com"],
+                    **{param: "value"},
+                    connection=mail.get_connection(),
+                )
+
+    def test_email_message_send_fail_silently_conflict(self):
+        email = mail.EmailMessage(
+            "Subject",
+            "Body",
+            "from@example.com",
+            ["to@example.com"],
+            connection=mail.get_connection(),
+        )
+        msg = (
+            "fail_silently cannot be used with a connection. "
+            "Pass fail_silently to get_connection() instead."
+        )
+        with self.assertRaisesMessage(TypeError, msg):
+            email.send(fail_silently=True)
+
+    def test_send_mass_mail_fail_silently_conflict(self):
+        datatuple = (("Subject", "Message", "from@example.com", ["to@example.com"]),)
+        msg = (
+            "fail_silently cannot be used with a connection. "
+            "Pass fail_silently to get_connection() instead."
+        )
+        with self.assertRaisesMessage(TypeError, msg):
+            mail.send_mass_mail(
+                datatuple, fail_silently=True, connection=mail.get_connection()
+            )
+
+    def test_send_mass_mail_auth_conflict(self):
+        datatuple = (("Subject", "Message", "from@example.com", ["to@example.com"]),)
+        msg = (
+            "auth_user and auth_password cannot be used with a connection. "
+            "Pass auth_user and auth_password to get_connection() instead."
+        )
+        for param in ["auth_user", "auth_password"]:
+            with (
+                self.subTest(param=param),
+                self.assertRaisesMessage(TypeError, msg),
+            ):
+                mail.send_mass_mail(
+                    datatuple, **{param: "value"}, connection=mail.get_connection()
+                )
+
+    def test_mail_admins_fail_silently_conflict(self):
+        msg = (
+            "fail_silently cannot be used with a connection. "
+            "Pass fail_silently to get_connection() instead."
+        )
+        with self.assertRaisesMessage(TypeError, msg):
+            mail.mail_admins(
+                "Subject",
+                "Message",
+                fail_silently=True,
+                connection=mail.get_connection(),
+            )
+
+    def test_mail_managers_fail_silently_conflict(self):
+        msg = (
+            "fail_silently cannot be used with a connection. "
+            "Pass fail_silently to get_connection() instead."
+        )
+        with self.assertRaisesMessage(TypeError, msg):
+            mail.mail_managers(
+                "Subject",
+                "Message",
+                fail_silently=True,
+                connection=mail.get_connection(),
+            )
+
 
 # RemovedInDjango70Warning.
 class MailDeprecatedPositionalArgsTests(SimpleTestCase):
@@ -2029,9 +2130,9 @@ class MailDeprecatedPositionalArgsTests(SimpleTestCase):
                 "from@example.com",
                 ["to@example.com"],
                 # Deprecated positional args:
-                True,
-                "username",
-                "password",
+                None,
+                None,
+                None,
                 mail.get_connection(),
                 "html message",
             )
@@ -2044,9 +2145,9 @@ class MailDeprecatedPositionalArgsTests(SimpleTestCase):
             send_mass_mail(
                 [],
                 # Deprecated positional args:
-                True,
-                "username",
-                "password",
+                None,
+                None,
+                None,
                 mail.get_connection(),
             )
 
@@ -2058,7 +2159,7 @@ class MailDeprecatedPositionalArgsTests(SimpleTestCase):
                 "subject",
                 "message",
                 # Deprecated positional args:
-                True,
+                None,
                 mail.get_connection(),
                 "html message",
             )
@@ -2071,7 +2172,7 @@ class MailDeprecatedPositionalArgsTests(SimpleTestCase):
                 "subject",
                 "message",
                 # Deprecated positional args:
-                True,
+                None,
                 mail.get_connection(),
                 "html message",
             )