=============
Sending email
=============

.. module:: django.core.mail
   :synopsis: Helpers to send email.

Django provides wrappers for Python's :mod:`email` and :mod:`smtplib` modules
to simplify composing and sending email. Django's email framework also supports
swapping in different delivery mechanisms: you can direct email to the console
or a file during development and an SMTP server or email service provider in
production.

The code lives in the ``django.core.mail`` module.

Quick examples
==============

Use :func:`send_mail` for straightforward email sending. For example, to send a
plain text message::

    from django.core.mail import send_mail

    send_mail(
        "Subject here",
        "Here is the message.",
        "from@example.com",
        ["to@example.com"],
    )

When additional email sending functionality is needed, use the
:ref:`EmailMessage <topic-email-message>` or :class:`EmailMultiAlternatives`
class. For example, to send a multipart email that includes both HTML and plain
text versions with a specific template and custom headers, you can use the
following approach::

    from django.core.mail import EmailMultiAlternatives
    from django.template.loader import render_to_string

    # First, render the plain text content.
    text_content = render_to_string(
        "templates/emails/my_email.txt",
        context={"my_variable": 42},
    )

    # Secondly, render the HTML content.
    html_content = render_to_string(
        "templates/emails/my_email.html",
        context={"my_variable": 42},
    )

    # Then, create a multipart email instance.
    msg = EmailMultiAlternatives(
        subject="Subject here",
        body=text_content,
        from_email="from@example.com",
        to=["to@example.com"],
        headers={"List-Unsubscribe": "<mailto:unsub@example.com>"},
    )

    # Lastly, attach the HTML content to the email instance and send.
    msg.attach_alternative(html_content, "text/html")
    msg.send()

.. _topic-email-configuration:

Configuring email
=================

New Django projects are not configured to send email by default. Instead, email
is printed to the console as a development aid (for projects created with
:djadmin:`startproject`) or results in a ``MailerDoesNotExist`` error (when the
:setting:`MAILERS` setting isn't defined).

Use the :setting:`MAILERS` setting to tell Django how to send email. For
example, to send through an SMTP server running on the local machine::

    MAILERS = {
        "default": {
            "BACKEND": "django.core.mail.backends.smtp.EmailBackend",
            "OPTIONS": {
                "host": "localhost",
            },
        },
    }

Django abstracts the email sending process into an "email backend" class.
:ref:`topic-email-backends` lists the email backends that come with Django.

The example above uses Django's :ref:`SMTP email backend
<topic-email-smtp-backend>`, which sends using the standard `SMTP`_ protocol.
This backend is useful for many production configurations, including SMTP
servers in your own infrastructure and most commercial email service providers
(ESPs). There are also :ref:`third-party email backends
<topic-third-party-email-backends>` available that integrate directly with ESP
APIs or add other sending features.

During development or testing you often don't want to send email at all.
Django's test runner :ref:`automatically overrides <topics-testing-email>` the
:setting:`MAILERS` configuration to substitute Django's :ref:`memory email
backend <topic-email-memory-backend>`. This prevents test cases from sending
real email and gives them access to the messages that would have been sent.
:ref:`topics/email:Configuring email for development` discusses some other
approaches.

.. versionchanged:: 6.1

    In earlier releases, Django defaulted to sending email through an SMTP
    server running on localhost, using the now-deprecated
    :setting:`EMAIL_BACKEND` and related settings.

.. deprecated:: 6.1

    Until Django 7.0, if the :setting:`MAILERS` setting is not defined then the
    earlier behavior still applies: Django will default to using an SMTP server
    on localhost (but will issue deprecation warnings). Starting in Django 7.0,
    attempts to send email without :setting:`MAILERS` defined will result in a
    ``MailerDoesNotExist`` error.

    Existing projects can opt into the new behavior early by adding
    :setting:`MAILERS` to ``settings.py``. See :ref:`migrating-to-mailers`.

Multiple mailers
----------------

Sometimes different types of email need to be sent in different ways: e.g.,
internal vs. external email, different SMTP servers for users in different
regions, using different services for transactional notifications and bulk
marketing email, etc.

The :setting:`MAILERS` setting can define multiple mail configurations. For
example::

    import os

    MAILERS = {
        "default": {
            "BACKEND": "django.core.mail.backends.smtp.EmailBackend",
            "OPTIONS": {
                "host": "smtp.example.net",
                "use_tls": True,
                "username": os.environ["EMAIL_ACCOUNT_ID"],
                "password": os.environ["EMAIL_API_KEY"],
            },
        },
        "notifications": {
            "BACKEND": "example.third.party.EmailBackend",
            "OPTIONS": {
                "api_key": os.environ["THIRD_PARTY_API_KEY"],
                "region": "eu",
            },
        },
        "admin": {
            "BACKEND": "django.core.mail.backends.smtp.EmailBackend",
            "OPTIONS": {
                "host": "localhost",
            },
        },
    }

This defines three mailer configurations:

* ``"default"`` sends through an SMTP server at ``smtp.example.net`` with a TLS
  secured connection. It reads an account id and API key from environment
  variables and uses them as the SMTP authentication username and password.
  (Many SMTP services use some variation of this authentication scheme.)

* ``"notifications"`` sends through a hypothetical commercial email service,
  using a third-party EmailBackend that connects directly to their API.
  (See :ref:`topic-third-party-email-backends` for pointers on locating real,
  community maintained email backend packages.)

* ``"admin"`` sends through an SMTP server running on ``localhost``, with no
  other options required.

With this configuration, you can provide the ``using`` argument to Django's
:ref:`email sending functions <topic-email-sending>` to specify a particular
mailer configuration::

    from django.core.mail import send_mail

    send_mail(
        "Account activated",
        "Congratulations, you're all ready to use our Django app!",
        "from@example.com",
        ["user@example.com"],
        using="notifications",
    )

If ``using`` is not specified, Django uses the mailer defined for the
``"default"`` configuration.

With reusable apps or Django features that send email for you, there may be an
option to use a specific mailer configuration. For example, Django's logging
:class:`~django.utils.log.AdminEmailHandler` allows specifying the mailer
configuration in its ``using`` option.

.. _SMTP: https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol

.. _topic-email-sending:

Sending messages
================

:mod:`!django.core.mail` provides functions for conveniently sending email, as
well as classes for building and sending more complex email messages with
attachments and multiple content types.

.. note::

    The character set of email sent with ``django.core.mail`` will be set to
    the value of your :setting:`DEFAULT_CHARSET` setting.

``send_mail()``
---------------

.. function:: send_mail(subject, message, from_email, recipient_list, *, fail_silently=False, auth_user=None, auth_password=None, connection=None, html_message=None)

``django.core.mail.send_mail()`` sends a single email message.

The ``subject``, ``message``, ``from_email`` and ``recipient_list`` parameters
are required.

* ``subject``: A string.
* ``message``: A string.
* ``from_email``: A string. If ``None``, Django will use the value of the
  :setting:`DEFAULT_FROM_EMAIL` setting.
* ``recipient_list``: A list of strings, each an email address. Each
  member of ``recipient_list`` will see the other recipients in the "To:"
  field of the email message.

The following parameters are optional, and must be given as keyword arguments
if used.

* ``fail_silently``: A boolean, default ``False``. If set ``True``,
  ``send_mail()`` will suppress some errors during sending. (The exact
  exceptions ignored depend on the email backend in use.)
* ``auth_user``: The optional username to use to authenticate to the SMTP
  server. If this isn't provided, Django will use the value of the
  :setting:`EMAIL_HOST_USER` setting.
* ``auth_password``: The optional password to use to authenticate to the
  SMTP server. If this isn't provided, Django will use the value of the
  :setting:`EMAIL_HOST_PASSWORD` setting.
* ``connection``: The optional email backend to use to send the mail.
  If unspecified, an instance of the default backend will be used.
  See the documentation on :ref:`Email backends <topic-email-backends>`
  for more details.
* ``html_message``: If ``html_message`` is provided, the resulting email will
  be a :mimetype:`multipart/alternative` email with ``message`` as the
  :mimetype:`text/plain` content type and ``html_message`` as the
  :mimetype:`text/html` content type.
* ``using``: An optional :setting:`MAILERS` alias to use to send the mail. If
  unspecified, the default mailer configuration will be used.

``fail_silently``, ``auth_user``, ``auth_password``, and ``connection`` are not
allowed with the ``using`` argument.

The return value will be the number of successfully delivered messages (which
can be ``0`` or ``1`` since it can only send one message).

.. deprecated:: 6.0

    Passing ``fail_silently`` and later parameters as positional arguments is
    deprecated.

.. deprecated:: 6.1

    The ``fail_silently``, ``auth_user``, ``auth_password``, and ``connection``
    arguments are deprecated. In most cases they can be replaced by ``using``
    with an appropriate :setting:`MAILERS` configuration. See
    :ref:`migrating-to-mailers-fail-silently`,
    :ref:`migrating-to-mailers-auth`, and
    :ref:`migrating-to-mailers-get-connection`.

.. versionchanged:: 6.1

    The ``using`` argument was added.

    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()``
--------------------

.. function:: send_mass_mail(datatuple, *, fail_silently=False, auth_user=None, auth_password=None, connection=None, using=None)

``django.core.mail.send_mass_mail()`` is intended to handle mass emailing.

``datatuple`` is a tuple in which each element is in this format::

    (subject, message, from_email, recipient_list)

``fail_silently``, ``auth_user``, ``auth_password`` and ``connection`` have the
same functions as in :func:`send_mail`. They must be given as keyword arguments
if used, and are not allowed with the ``using`` argument.

The keyword argument ``using`` is an optional :setting:`MAILERS` alias to use
to send the mail. If unspecified, the default mailer configuration will be
used.

Each separate element of ``datatuple`` results in a separate email message.
As in :func:`send_mail`, recipients in the same ``recipient_list`` will all see
the other addresses in the email messages' "To:" field.

For example, the following code would send two different messages to
two different sets of recipients; however, only one connection to the
mail server would be opened::

    message1 = (
        "Subject here",
        "Here is the message",
        "from@example.com",
        ["first@example.com", "other@example.com"],
    )
    message2 = (
        "Another Subject",
        "Here is another message",
        "from@example.com",
        ["second@test.com"],
    )
    send_mass_mail((message1, message2))

The return value will be the number of successfully delivered messages.

.. deprecated:: 6.0

    Passing ``fail_silently`` and later parameters as positional arguments is
    deprecated.

.. deprecated:: 6.1

    The ``fail_silently``, ``auth_user``, ``auth_password``, and ``connection``
    arguments are deprecated. In most cases they can be replaced by ``using``
    with an appropriate :setting:`MAILERS` configuration. See
    :ref:`migrating-to-mailers-fail-silently`,
    :ref:`migrating-to-mailers-auth`, and
    :ref:`migrating-to-mailers-get-connection`.

.. versionchanged:: 6.1

    The ``using`` argument was added.

    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()``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The main difference between :func:`send_mass_mail` and repeatedly calling
:func:`send_mail` is that :func:`send_mail` opens a connection to the mail
server each time it's executed, while :func:`send_mass_mail` uses a single
connection for all of its messages. This makes :func:`send_mass_mail` slightly
more efficient.

:func:`send_mail` with multiple ``to`` addresses sends a single email message,
with ``john@example.com`` and ``jane@example.com`` both appearing in the "To:"
field::

    send_mail(
        "Subject",
        "Message.",
        "from@example.com",
        ["john@example.com", "jane@example.com"],
    )

:func:`send_mass_mail` sends a separate message per ``datatuple`` element, so
``john@example.com`` and ``jane@example.com`` each receive their own email::

    datatuple = (
        ("Subject", "Message.", "from@example.com", ["john@example.com"]),
        ("Subject", "Message.", "from@example.com", ["jane@example.com"]),
    )
    send_mass_mail(datatuple)

``mail_admins()``
-----------------

.. function:: mail_admins(subject, message, *, fail_silently=False, connection=None, html_message=None, using=None)

``django.core.mail.mail_admins()`` is a shortcut for sending an email to the
site admins, as defined in the :setting:`ADMINS` setting.

``mail_admins()`` prefixes the subject with the value of the
:setting:`EMAIL_SUBJECT_PREFIX` setting, which is ``"[Django] "`` by default.

The "From:" header of the email will be the value of the
:setting:`SERVER_EMAIL` setting.

This method exists for convenience and readability.

If ``html_message`` is provided, the resulting email will be a
:mimetype:`multipart/alternative` email with ``message`` as the
:mimetype:`text/plain` content type and ``html_message`` as the
:mimetype:`text/html` content type.

The keyword argument ``using`` is an optional :setting:`MAILERS` alias to use
to send the mail. If unspecified, the default mailer configuration will be
used.

.. deprecated:: 6.0

    Passing ``fail_silently`` and later parameters as positional arguments is
    deprecated.

.. deprecated:: 6.1

    The ``fail_silently`` and ``connection`` arguments are deprecated. In most
    cases they can be replaced by ``using`` with an appropriate
    :setting:`MAILERS` configuration. See
    :ref:`migrating-to-mailers-fail-silently` and
    :ref:`migrating-to-mailers-get-connection`.

.. versionchanged:: 6.1

    The ``using`` argument was added.

    Older versions ignored ``fail_silently=True`` when a ``connection``
    was also provided. This now raises a ``TypeError``.

``mail_managers()``
-------------------

.. function:: mail_managers(subject, message, *, fail_silently=False, connection=None, html_message=None, using=None)

``django.core.mail.mail_managers()`` is just like ``mail_admins()``, except it
sends an email to the site managers, as defined in the :setting:`MANAGERS`
setting.

The keyword argument ``using`` is an optional :setting:`MAILERS` alias to use
to send the mail. If unspecified, the default mailer configuration will be
used.

.. deprecated:: 6.0

    Passing ``fail_silently`` and later parameters as positional arguments is
    deprecated.

.. deprecated:: 6.1

    The ``fail_silently`` and ``connection`` arguments are deprecated. In most
    cases they can be replaced by ``using`` with an appropriate
    :setting:`MAILERS` configuration. See
    :ref:`migrating-to-mailers-fail-silently` and
    :ref:`migrating-to-mailers-get-connection`.

.. versionchanged:: 6.1

    The ``using`` argument was added.

    Older versions ignored ``fail_silently=True`` when a ``connection``
    was also provided. This now raises a ``TypeError``.

.. _topic-email-message:

The ``EmailMessage`` class
--------------------------

Django's :func:`send_mail` and :meth:`send_mass_mail` functions are actually
thin wrappers that make use of the :class:`EmailMessage` class.

Not all features of the :class:`EmailMessage` class are available through the
:func:`send_mail` and related wrapper functions. If you wish to use advanced
features, such as BCC'ed recipients, file attachments, or multi-part email,
you'll need to create :class:`EmailMessage` instances directly.

.. note::
    This is a design feature. :func:`send_mail` and related functions were
    originally the only interface Django provided. However, the list of
    parameters they accepted was slowly growing over time. It made sense to
    move to a more object-oriented design for email messages and retain the
    original functions only for backwards compatibility.

:class:`EmailMessage` is responsible for creating the email message itself. The
:ref:`email backend <topic-email-backends>` is then responsible for sending the
email.

For convenience, :class:`EmailMessage` provides a :meth:`~EmailMessage.send`
method for sending a single email. If you need to send multiple messages, the
email backend API :ref:`provides an alternative
<topics-sending-multiple-emails>`.

.. class:: EmailMessage

    The :class:`!EmailMessage` class is initialized with the following
    parameters. All parameters are optional and can be set at any time prior
    to calling the :meth:`send` method.

    The first four parameters can be passed as positional or keyword arguments,
    but must be in the given order if positional arguments are used:

    * ``subject``: The subject line of the email.

    * ``body``: The body text. This should be a plain text message.

    * ``from_email``: The sender's address. Both ``fred@example.com`` and
      ``"Fred" <fred@example.com>`` forms are supported (see
      :ref:`formatting-addresses`). If omitted, the
      :setting:`DEFAULT_FROM_EMAIL` setting is used.

    * ``to``: A list or tuple of recipient addresses.

    The following parameters must be given as keyword arguments if used:

    * ``cc``: A list or tuple of recipient addresses used in the "Cc" header
      when sending the email.

    * ``bcc``: A list or tuple of addresses used for blind carbon copies when
      sending the email.

    * ``reply_to``: A list or tuple of recipient addresses used in the
      "Reply-To" header when sending the email.

    * ``attachments``: A list of attachments to put on the message. Each can
      be an instance of :class:`~email.message.MIMEPart` or
      :class:`EmailAttachment`, or a tuple with attributes
      ``(filename, content, mimetype)``.

      .. versionchanged:: 6.0

          Support for :class:`~email.message.MIMEPart` objects in the
          ``attachments`` list was added.

      .. deprecated:: 6.0

          Support for Python's legacy :class:`~email.mime.base.MIMEBase`
          objects in ``attachments`` is deprecated. Use
          :class:`~email.message.MIMEPart` instead.

    * ``headers``: A dictionary of extra headers to put on the message. The
      keys are the header name, values are the header values. It's up to the
      caller to ensure header names and values are in the correct format for
      an email message. The corresponding attribute is ``extra_headers``.

    * ``connection``: An :ref:`email backend <topic-email-backends>` instance.
      This parameter is ignored when using
      :ref:`send_messages() <topics-sending-multiple-emails>`.

      .. deprecated:: 6.1

        The ``connection`` argument is deprecated. Instead, define a
        :setting:`MAILERS` configuration with the desired connection options,
        and then call :meth:`EmailMessage.send(using="...") <send>` with that
        configuration's alias. See :ref:`migrating-to-mailers`.

    .. deprecated:: 6.0

        Passing all except the first four parameters as positional arguments is
        deprecated.

    For example::

        from django.core.mail import EmailMessage

        email = EmailMessage(
            subject="Hello",
            body="Body goes here",
            from_email="from@example.com",
            to=["to1@example.com", "to2@example.com"],
            bcc=["bcc@example.com"],
            reply_to=["another@example.com"],
            headers={"Message-ID": "foo"},
        )

    The class has the following methods:

    .. method:: send(fail_silently=False, *, using=None)

        Sends the message. Returns ``1`` if the message was sent successfully,
        otherwise ``0``. (An empty list of recipients returns ``0`` -- it will
        not raise an exception.)

        The optional ``using`` keyword argument specifies a :setting:`MAILERS`
        alias to use to send the mail. If not given, the default mailer
        configuration will be used.

        If a deprecated connection was specified when the email was
        constructed, that connection will be used. Providing both a connection
        and ``using`` will raise an error.

        If the deprecated keyword argument ``fail_silently`` is ``True``,
        certain backend-dependent exceptions while sending the message will be
        ignored. Providing both ``fail_silently`` and ``using`` will raise an
        error.

        .. versionchanged:: 6.1

            The ``using`` argument was added.

            Older versions ignored ``fail_silently=True`` when a ``connection``
            was also provided. This now raises a ``TypeError``.

        .. deprecated:: 6.1

            The ``fail_silently`` argument is deprecated. See
            :ref:`migrating-to-mailers-fail-silently` for alternatives.

    .. method:: message(*, policy=email.policy.default)

        Constructs and returns a Python :class:`email.message.EmailMessage`
        object representing the message to be sent.

        The keyword argument ``policy`` allows specifying the set of rules for
        updating and serializing the representation of the message. It must be
        an :mod:`email.policy.Policy <email.policy>` object. Defaults to
        :data:`email.policy.default`. In certain cases you may want to use
        :data:`~email.policy.SMTP`, :data:`~email.policy.SMTPUTF8` or a custom
        policy. For example, the :ref:`SMTP email backend
        <topic-email-smtp-backend>` uses the :data:`~email.policy.SMTP` policy
        to ensure ``\r\n`` line endings as required by the SMTP protocol.

        If you ever need to extend Django's :class:`EmailMessage` class,
        you'll probably want to override this method to put the content you
        want into the Python EmailMessage object.

        .. versionchanged:: 6.0

            The ``policy`` keyword argument was added and the return type was
            updated to an instance of :class:`~email.message.EmailMessage`.

    .. method:: recipients()

        Returns a list of all the recipients of the message, whether they're
        recorded in the ``to``, ``cc`` or ``bcc`` attributes. This is another
        method you might need to override when subclassing, because the SMTP
        server needs to be told the full list of recipients when the message
        is sent. If you add another way to specify recipients in your class,
        they need to be returned from this method as well.

    .. method:: attach(filename, content, mimetype)
                attach(mimepart)

        Creates a new attachment and adds it to the message. There are two ways
        to call :meth:`!attach`:

        * You can pass it three arguments: ``filename``, ``content`` and
          ``mimetype``. ``filename`` is the name of the file attachment as it
          will appear in the email, ``content`` is the data that will be
          contained inside the attachment and ``mimetype`` is the optional MIME
          type for the attachment. If you omit ``mimetype``, the MIME content
          type will be guessed from the filename of the attachment.

          For example::

              message.attach("design.png", img_data, "image/png")

          If you specify a ``mimetype`` of :mimetype:`message/rfc822`,
          ``content`` can be a :class:`django.core.mail.EmailMessage` or
          Python's :class:`email.message.EmailMessage` or
          :class:`email.message.Message`.

          For a ``mimetype`` starting with :mimetype:`text/`, content is
          expected to be a string. Binary data will be decoded using UTF-8,
          and if that fails, the MIME type will be changed to
          :mimetype:`application/octet-stream` and the data will be attached
          unchanged.

        * Or for attachments requiring additional headers or parameters, you
          can pass :meth:`!attach` a single Python
          :class:`~email.message.MIMEPart` object. This will be attached
          directly to the resulting message. For example, to attach an inline
          image with a :mailheader:`Content-ID`::

              import email.utils
              from email.message import MIMEPart
              from django.core.mail import EmailMultiAlternatives

              message = EmailMultiAlternatives(...)
              image_data_bytes = ...  # Load image as bytes

              # Create a random Content-ID, including angle brackets
              cid = email.utils.make_msgid()
              inline_image = email.message.MIMEPart()
              inline_image.set_content(
                  image_data_bytes,
                  maintype="image",
                  subtype="png",  # or "jpeg", etc. depending on the image type
                  disposition="inline",
                  cid=cid,
              )
              message.attach(inline_image)
              # Refer to Content-ID in HTML without angle brackets
              message.attach_alternative(f'… <img src="cid:{cid[1:-1]}"> …', "text/html")

          Python's :meth:`email.contentmanager.set_content` documentation
          describes the supported arguments for ``MIMEPart.set_content()``.

          .. versionchanged:: 6.0

              Support for :class:`~email.message.MIMEPart` attachments was
              added.

          .. deprecated:: 6.0

              Support for :class:`email.mime.base.MIMEBase` attachments is
              deprecated. Use :class:`~email.message.MIMEPart` instead.

    .. method:: attach_file(path, mimetype=None)

        Creates a new attachment using a file from your filesystem. Call it
        with the path of the file to attach and, optionally, the MIME type to
        use for the attachment. If the MIME type is omitted, it will be guessed
        from the filename. You can use it like this::

            message.attach_file("/images/weather_map.png")

        For MIME types starting with :mimetype:`text/`, binary data is handled
        as in :meth:`attach`.

.. class:: EmailAttachment

    A named tuple to store attachments to an email.

    The named tuple has the following indexes:

    * ``filename``
    * ``content``
    * ``mimetype``

Sending alternative content types
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sending multiple content versions
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

It can be useful to include multiple versions of the content in an email; the
classic example is to send both text and HTML versions of a message. With
Django's email library, you can do this using the
:class:`EmailMultiAlternatives` class.

.. class:: EmailMultiAlternatives

    A subclass of :class:`EmailMessage` that allows additional versions of the
    message body in the email via the :meth:`attach_alternative` method. This
    directly inherits all methods (including the class initialization) from
    :class:`EmailMessage`.

    .. attribute:: alternatives

        A list of :class:`EmailAlternative` named tuples.
        This is particularly useful in tests::

            self.assertEqual(len(msg.alternatives), 1)
            self.assertEqual(msg.alternatives[0].content, html_content)
            self.assertEqual(msg.alternatives[0].mimetype, "text/html")

        Alternatives should only be added using the :meth:`attach_alternative`
        method, or passed to the constructor.

    .. method:: attach_alternative(content, mimetype)

        Attach an alternative representation of the message body in the email.

        For example, to send a text and HTML combination, you could write::

            from django.core.mail import EmailMultiAlternatives

            subject = "hello"
            from_email = "from@example.com"
            to = "to@example.com"
            text_content = "This is an important message."
            html_content = "<p>This is an <strong>important</strong> message.</p>"
            msg = EmailMultiAlternatives(subject, text_content, from_email, [to])
            msg.attach_alternative(html_content, "text/html")
            msg.send()

    .. method:: body_contains(text)

        Returns a boolean indicating whether the provided ``text`` is
        contained in the email ``body`` and in all attached MIME type
        ``text/*`` alternatives.

        This can be useful when testing emails. For example::

            def test_contains_email_content(self):
                subject = "Hello World"
                from_email = "from@example.com"
                to = "to@example.com"
                msg = EmailMultiAlternatives(subject, "I am content.", from_email, [to])
                msg.attach_alternative("<p>I am content.</p>", "text/html")

                self.assertIs(msg.body_contains("I am content"), True)
                self.assertIs(msg.body_contains("<p>I am content.</p>"), False)

.. class:: EmailAlternative

    A named tuple to store alternative versions of email content.

    The named tuple has the following indexes:

    * ``content``
    * ``mimetype``

Updating the default content type
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

By default, the MIME type of the ``body`` parameter in an :class:`EmailMessage`
is ``"text/plain"``. It is good practice to leave this alone, because it
guarantees that any recipient will be able to read the email, regardless of
their mail client. However, if you are confident that your recipients can
handle an alternative content type, you can use the ``content_subtype``
attribute on the :class:`EmailMessage` class to change the main content type.
The major type will always be ``"text"``, but you can change the subtype. For
example::

    msg = EmailMessage(subject, html_content, from_email, [to])
    msg.content_subtype = "html"  # Main content is now text/html
    msg.send()

Safely sending email
--------------------

Any public website that can send email will eventually be targeted by attempts
to abuse it for spam, phishing, or other malicious content. While a complete
discussion of vulnerabilities in sending email is beyond the scope of Django's
documentation, there are many references available on the web. Two good
starting points are:

* Princeton University's guidance on `preventing email abuse in web forms`_.
  Although this is an internal reference for users of Princeton's Drupal Site
  Builder, nearly all of its advice applies equally to sites built with Django
  (or any web framework).

* OWASP's `Email Validation and Verification in Identity Systems Cheat Sheet`_.
  This primarily covers using email in authentication contexts. While many of
  its recommendations are handled by :mod:`django.contrib.auth` and other
  Django features, items like rate limiting and securing email change workflows
  are the developer's responsibility.

Thinking through how email might be abused (and taking steps to mitigate it) is
especially important if your site can send to unverified addresses. Features
like newsletter sign-up, contact forms that cc or auto-reply to the sender, and
"share this page" can be attractive targets.

.. _preventing email abuse in web forms:
    https://sitebuilder.princeton.edu/site-administration/spam
.. _Email Validation and Verification in Identity Systems Cheat Sheet:
    https://cheatsheetseries.owasp.org/cheatsheets/Email_Validation_and_Verification_Cheat_Sheet.html

.. _formatting-addresses:

Formatting email addresses
~~~~~~~~~~~~~~~~~~~~~~~~~~

Email addresses allow a "friendly" display name alongside the ``user@domain``
address. For example, you could include your company name in the
:setting:`DEFAULT_FROM_EMAIL` setting::

    DEFAULT_FROM_EMAIL = '"Example, Inc." <contact@example.com>'

The double quotes around ``"Example, Inc."`` are needed so the comma isn't read
as separating two different addresses. A fixed address, written out by hand as
in the example above, is safe, but composing one from variable parts
(especially untrusted input) needs more care.

.. warning::

    Never use string formatting to build an email address from variable parts.
    For example, ``f'"{name}" <{email}>'`` is **unsafe**.

Email address headers have complex syntax rules (much like HTML or SQL), so
constructing them by combining strings creates an injection vulnerability. Even
if you've :class:`validated <.EmailValidator>` the format of ``email``, an
attacker could exploit the ``name`` portion to inject additional addresses.

To avoid this, always use a well-tested library specifically meant to format
email addresses, like Python's :class:`email.headerregistry.Address` class (the
replacement for the legacy :func:`~email.utils.formataddr` function, which does
not support internationalized domain names).

For example, to include a user's full name when sending them email (where
``user`` is an instance of the default :class:`.User` model)::

    from django.core.mail import send_mail
    from email.headerregistry import Address


    def send_mail_to_user(user, subject, body, from_email=None):
        # Safely create an email address with the user's name.
        # (addr_spec is the technical term for the user@domain address.)
        address = Address(
            display_name=user.get_full_name(),
            addr_spec=user.email,
        )
        send_mail(subject, body, from_email, [address])

Django's built-in email backends support using
:class:`~email.headerregistry.Address` objects directly in any address field,
as shown here. So do many custom and third-party email backends. But if this
causes a ``TypeError`` or other problem with a particular backend, use
``str(address)`` to convert the object to a safe, properly formatted string.

Preventing header injection
~~~~~~~~~~~~~~~~~~~~~~~~~~~

`Email header injection`_ is a security exploit in which an attacker
manipulates email headers to change the intended sender or recipients, subject,
or potentially even the entire visible message body.

One type of header injection exploits address header syntax. You are
responsible for preventing this when constructing email addresses from
user-supplied input, as described in :ref:`formatting-addresses` above.

Another (perhaps better understood) attack, CRLF injection, uses carriage
return and line feed characters to insert additional headers into the email.
Django prevents this by raising a :exc:`ValueError` if those characters appear
in any header field when trying to send the message.

.. versionchanged:: 6.0

    Older versions raised ``django.core.mail.BadHeaderError`` for some
    invalid headers. This has been replaced with :exc:`!ValueError`.

Django's CRLF protection relies on using Python's modern
:class:`~email.policy.EmailPolicy` in Django's :meth:`EmailMessage.message`.
Custom email backends that don't call that function, or that call it with the
legacy :data:`~email.policy.compat32` policy, are responsible for implementing
their own CRLF injection prevention.

.. _Email header injection: https://en.wikipedia.org/wiki/Email_injection

.. _topics-sending-multiple-emails:

Sending many messages efficiently
---------------------------------

Establishing and closing an SMTP connection (or any other network connection,
for that matter) is an expensive process. If you have a lot of emails to send,
it makes sense to reuse an SMTP connection, rather than creating and
destroying a connection every time you want to send an email.

There are two ways to tell an email backend to reuse a connection. Both involve
obtaining an email backend instance from :data:`.mail.mailers` and using the
:ref:`backend's API <topic-email-backend-api>`.

The first approach is to use the backend's ``send_messages()`` method. This
takes a list of :class:`EmailMessage` (or subclass) instances, and sends them
all using that single connection.

For example, if you have a function called ``get_notification_emails()`` that
returns a list of :class:`EmailMessage` objects representing some periodic
email you wish to send out, you could send these emails using a single call to
``send_messages()``::

    from django.core import mail

    email_list = get_notification_emails()
    # Use the default mailer. You could substitute
    # mail.mailers["alias"] for a specific mailer.
    backend = mail.mailers.default
    backend.send_messages(email_list)

In this example, the call to ``send_messages()`` opens a connection on the
backend, sends the list of messages, and then closes the connection again.
(This is how :func:`send_mass_mail` is implemented.)

The second approach is to use the ``open()`` and ``close()`` methods on the
email backend to manually control the connection. ``send_messages()`` will not
open or close the connection if it is already open, so if you
manually open the connection, you can control when it is closed. For example::

    from django.core import mail

    # Use the "notifications" mailer configuration.
    backend = mail.mailers["notifications"]

    # Manually open the connection.
    backend.open()

    # Construct an email message. (Passing None as the third argument
    # uses settings.DEFAULT_FROM_EMAIL as the "From:" address.)
    email1 = mail.EmailMessage("Hi", "Message", None, ["to1@example.com"])
    # Send the email. The connection was already open, so send_messages()
    # leaves it open after sending.
    backend.send_messages([email1])

    # Construct and send two more messages. The connection is still open.
    email2 = mail.EmailMessage("Hi", "Message", None, ["to2@example.com"])
    email3 = mail.EmailMessage("Hi", "Message", None, ["to3@example.com"])
    backend.send_messages([email2, email3])

    # Because we opened it, we need to manually close the connection.
    backend.close()

When you manually open a backend's connection, you are responsible for ensuring
it gets closed. The example above actually has a bug: if an exception occurs
while sending the messages, the connection will not be closed. This can be
fixed with a ``try``-``finally`` statement, but using the backend instance as a
context manager is preferable, as it automatically calls ``open()`` and
``close()`` as needed.

This is equivalent to the previous example, but uses the backend as a
:ref:`context manager <context-managers>` to avoid leaving the connection open
on errors::

    from django.core import mail

    # Use mail.mailers[...] as a context manager.
    with mail.mailers["notifications"] as backend:
        # The backend connection is automatically opened inside the context.
        email1 = mail.EmailMessage("Hi", "Message", None, ["to1@example.com"])
        backend.send_messages([email1])

        # The connection is still open, and is reused for the second send.
        email2 = mail.EmailMessage("Hi", "Message", None, ["to2@example.com"])
        email3 = mail.EmailMessage("Hi", "Message", None, ["to3@example.com"])
        backend.send_messages([email2, email3])

    # After exiting the context (either normally or because of an error),
    # the backend connection is automatically closed.

.. _topic-email-backends:

Email backends
==============

The actual sending of an email is handled by the email backend.

Django comes with several email backends. With the exception of the SMTP
backend, these are mainly useful during testing and development. If the
built-in backends don't meet your needs there are :ref:`third-party packages
<topic-third-party-email-backends>` available. You can also subclass one of the
built-in backends to change its behavior, or even :ref:`write your own email
backend <topic-custom-email-backend>`.

.. _topic-email-smtp-backend:

SMTP backend
------------

The SMTP email backend connects to an SMTP server to send email. To use it, set
:setting:`BACKEND <MAILERS-BACKEND>` to
``"django.core.mail.backends.smtp.EmailBackend"``.

The SMTP backend supports these :setting:`OPTIONS <MAILERS-OPTIONS>`:

* ``"host"`` (required): the SMTP server hostname or IP address.

* ``"port"``: the port number to connect to on the SMTP host. If omitted,
  uses the standard port for the connection protocol depending on the
  ``"use_tls"`` and ``"use_ssl"`` options: ``587`` for TLS, ``465`` for SSL,
  or ``25`` for an unsecured connection.

* ``"username"`` and ``"password"``: set these if your server requires SMTP
  authentication ("SMTP AUTH" credentials, sometimes called SMTP login).

  Although the username is often an email address, it should not be confused
  with default "From:" addresses. Those are defined by the
  :setting:`DEFAULT_FROM_EMAIL` and :setting:`SERVER_EMAIL` settings.

* ``"use_tls"`` or ``"use_ssl"``: set one of these options to ``True`` to
  connect to the SMTP server using a secure protocol -- ``"use_tls"`` for
  explicit TLS or ``"use_ssl"`` for SSL (implicit TLS).

* ``"ssl_certfile"`` and ``"ssl_keyfile"``: if the SMTP server's SSL/TLS
  connection requires client certificate authentication, use these options to
  specify the paths to a PEM-formatted certificate chain file and private key
  file. (The key file can be omitted if the certificate file includes the
  private key.)

  These options are not intended for use with a private certificate authority
  or self-signed SMTP server certificate. See
  :ref:`topic-email-smtp-private-ca` below.

  Note that these options don't result in checking certificate validity. They
  are passed to the underlying SSL connection. Refer to the documentation of
  Python's :meth:`ssl.SSLContext.wrap_socket` method for details on how the
  certificate chain file and private key file are handled.

* ``"timeout"``: the timeout (in seconds) for connecting to the SMTP server and
  other blocking operations. If not specified, the value is obtained from
  :func:`socket.getdefaulttimeout`, which defaults to no timeout (``None``)
  meaning SMTP operations can block indefinitely.

* ``"fail_silently"``: set to ``True`` to ignore certain errors while sending
  a message. All :exc:`OSError`\s are ignored while opening the SMTP
  connection, and :exc:`smtplib.SMTPException` errors are ignored while
  communicating with the server. This will suppress both transient network
  glitches and also serious configuration problems. However, it does not ignore
  *all* errors, and problems with serializing the message will not fail
  silently. (This option is available for backward compatibility but is not
  recommended for typical use.)

Example::

    MAILERS = {
        "default": {
            "BACKEND": "django.core.mail.backends.smtp.EmailBackend",
            "OPTIONS": {
                "host": "smtp.example.net",
                "use_tls": True,
                "username": "my-app",
                "password": os.environ["MY_APP_SMTP_PASSWORD"],
                "timeout": 10,
            },
        },
    }

.. deprecated:: 6.1

    When the :setting:`MAILERS` setting is not defined, Django uses the SMTP
    backend as the default mailer (the default :setting:`EMAIL_BACKEND`),
    connecting to localhost on port 25. This behavior will be removed in Django
    7.0, which will not have a default mailer configuration.

    When the SMTP backend is used without :setting:`MAILERS` defined,
    the options listed above are obtained from the deprecated
    :setting:`EMAIL_HOST`, :setting:`EMAIL_PORT`, :setting:`EMAIL_HOST_USER`,
    :setting:`EMAIL_HOST_PASSWORD`, :setting:`EMAIL_USE_TLS`,
    :setting:`EMAIL_USE_SSL`, :setting:`EMAIL_SSL_KEYFILE`,
    :setting:`EMAIL_SSL_CERTFILE`, and :setting:`EMAIL_TIMEOUT` settings,
    respectively. (There is no setting equivalent to the ``"fail_silently"``
    option.)

.. RemovedInDjango70Warning: class documentation for smtp.EmailBackend.

.. class:: backends.smtp.EmailBackend

    Directly instantiating an ``EmailBackend`` class is not recommended. Use
    :data:`mailers` to obtain a backend instance.

    When constructed directly (without going through :data:`mailers`), the SMTP
    ``EmailBackend`` class accepts the options listed above as keyword
    arguments. Default values come from the corresponding, deprecated
    ``EMAIL_*`` settings. ``host`` is not required and defaults to
    ``"localhost"``, and ``port`` defaults to ``25`` even if ``use_tls`` or
    ``use_ssl`` is True.

    When the :setting:`MAILERS` setting is defined, attempting to directly
    create an SMTP ``EmailBackend`` will raise an ``AttributeError``.

    .. deprecated:: 6.1

        Directly constructing an instance of an ``EmailBackend`` class will be
        unsupported in Django 7.0. Undocumented use will result in different
        default argument handling compared to earlier releases.

.. _topic-email-smtp-private-ca:

Private and self-signed SMTP server certificates
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If the SMTP server uses an SSL certificate from a private certificate authority
(CA), the CA's root certificate should be added to the system CA bundle on the
client (where Django is running). Likewise, if the server uses a self-signed
certificate, it should be added to the client's system CA bundle so it can be
trusted. (The SMTP backend's ``"ssl_certfile"`` option cannot be used for CA
roots or self-signed certificates.)

Follow platform-specific instructions for adding to the system CA bundle. If
modifying the system bundle is not possible or desired, an alternative is using
OpenSSL's ``SSL_CERT_FILE`` or ``SSL_CERT_DIR`` environment variables to
specify a custom certificate bundle.

For more complex scenarios, the SMTP backend can be subclassed to add root
certificates to its ``ssl_context`` using
:meth:`ssl.SSLContext.load_verify_locations`.

.. _topic-email-console-backend:

Console backend
---------------

Instead of sending out real emails, the console backend writes the emails that
would be sent to the standard output. To use it, set :setting:`BACKEND
<MAILERS-BACKEND>` to ``"django.core.mail.backends.console.EmailBackend"``.

The console backend supports these :setting:`OPTIONS <MAILERS-OPTIONS>`:

* ``"stream"``: a stream-like object to write to. Defaults to ``stdout``.

* ``"fail_silently"``: set to ``True`` to ignore *all* errors while writing the
  message to the stream, including errors serializing the message. (This option
  is available for backward compatibility but is not recommended.)

This backend is not intended for use in production -- it is provided as a
convenience that can be used during development.

.. versionchanged:: 6.1

    The settings file created by :djadmin:`startproject` now defines
    :setting:`MAILERS` with the console backend as the default configuration.

.. _topic-email-file-backend:

File backend
------------

The file backend writes emails to a file. A new file is created for each new
session that is opened on this backend. To use it, set :setting:`BACKEND
<MAILERS-BACKEND>` to ``"django.core.mail.backends.filebased.EmailBackend"``.

The file backend supports these :setting:`OPTIONS <MAILERS-OPTIONS>`:

* ``"file_path"`` (required): the directory to which the files are written. Can
  be a string or a :class:`pathlib.Path` object. If the directory does not
  exist, the file backend will attempt to create it.

* ``"fail_silently"``: set to ``True`` to ignore *all* errors while writing the
  message to the file -- including errors serializing the message -- but *not*
  errors related to ensuring the file path directory exists. (This option is
  available for backward compatibility but is not recommended.)

This backend is not intended for use in production -- it is provided as a
convenience that can be used during development.

.. deprecated:: 6.1

    When the file backend is used without the :setting:`MAILERS` setting
    defined, it will get its ``file_path`` option from the
    :setting:`EMAIL_FILE_PATH` setting.

.. _topic-email-memory-backend:

In-memory backend
-----------------

The ``'locmem'`` backend stores messages in a special attribute of the
``django.core.mail`` module. The ``outbox`` attribute is created when the first
message is sent. It's a list with an :class:`EmailMessage` instance for each
message that would be sent. Messages in the outbox are annotated with a
``sent_using`` attribute that identifies the :setting:`MAILERS` alias used to
send the message.

To use the in-memory backend, set :setting:`BACKEND <MAILERS-BACKEND>` to
``"django.core.mail.backends.locmem.EmailBackend"``. It does not support any
:setting:`OPTIONS <MAILERS-OPTIONS>`.

Django's test runner :ref:`automatically switches to this backend for testing
<topics-testing-email>`.

This backend is not intended for use in production -- it is provided as a
convenience that can be used during development and testing.

.. versionchanged:: 6.1

    The ``sent_using`` attribute was added to messages in the outbox.

.. _topic-email-dummy-backend:

Dummy backend
-------------

As the name suggests the dummy backend does nothing with your messages. To use
it, set :setting:`BACKEND <MAILERS-BACKEND>` to
``"django.core.mail.backends.dummy.EmailBackend"``. It does not support any
:setting:`OPTIONS <MAILERS-OPTIONS>`.

This backend is not intended for use in production -- it is provided as a
convenience that can be used during development.

.. _topic-third-party-email-backends:

Third-party backends
--------------------

.. admonition:: There are community-maintained solutions!

    Django has a vibrant ecosystem. There are email backends
    highlighted on the `Community Ecosystem`_ page. The Django Packages
    `Email grid`_ has even more options for you!

Third-party email backends are available that:

* Integrate directly with commercial email service providers' APIs (which often
  have extra functionality not available through SMTP).
* Offload email sending to asynchronous task queues.
* Add features to other email backends, such as enforcing do-not-send lists or
  logging sent messages.
* Provide development and debugging tools, such as sandbox capture and
  in-browser email previews.

.. _Community Ecosystem: https://www.djangoproject.com/community/ecosystem/#email-notifications
.. _Email grid: https://djangopackages.org/grids/g/email/

.. _topic-custom-email-backend:

Defining a custom email backend
-------------------------------

If you need to change how emails are sent you can write your own email backend.
To use a custom backend, set :setting:`BACKEND <MAILERS-BACKEND>` to the Python
import path for your backend class and :setting:`OPTIONS <MAILERS-OPTIONS>` to
any ``__init__()`` keyword arguments your backend supports.

Custom email backends should subclass ``BaseEmailBackend`` that is located in
the ``django.core.mail.backends.base`` module. A custom email backend must
implement the ``send_messages(email_messages)`` method. This method receives a
list of :class:`EmailMessage` instances and returns the number of successfully
delivered messages. If your backend has any concept of a persistent session or
connection, you should also implement the ``open()`` and ``close()`` methods.
Refer to ``smtp.EmailBackend`` for a reference implementation.

.. _topic-mailers:

Obtaining an instance of an email backend
-----------------------------------------

The ``mailers`` factory in :mod:`!django.core.mail` returns instances of email
backends.

.. data:: mailers

    .. versionadded:: 6.1

    You can access the mailers configured in the :setting:`MAILERS` setting
    through a dict-like object: ``django.core.mail.mailers``:

    .. code-block:: pycon

        >>> from django.core.mail import mailers
        >>> mailers["notifications"]

    If the named key is not defined, a ``MailerDoesNotExist`` error will be
    raised. Other configuration problems will raise an ``InvalidMailer`` error.

.. data:: mailers.default

    .. versionadded:: 6.1

    As a shortcut, the default mailer can be accessed through
    ``django.core.mail.mailers.default``:

    .. code-block:: pycon

        >>> from django.core.mail import mailers
        >>> mailers.default

    This is equivalent to ``mailers["default"]``. If no default mailer has
    been configured, a ``MailerDoesNotExist`` error will be raised.

    .. deprecated:: 6.1

        If the :setting:`MAILERS` setting is not defined, ``mailers.default``
        will create an email backend instance from the deprecated
        :setting:`EMAIL_BACKEND` and related settings. This supports backward
        compatibility with Django 6.0 and earlier.

        This behavior (and those settings) will be removed in Django 7.0.

.. function:: get_connection(backend=None, *, fail_silently=False, **kwargs)

    The deprecated :func:`!django.core.mail.get_connection` function creates
    and returns an instance of an email backend. Its behavior depends on the
    :setting:`MAILERS` setting and how the function is called.

    If the :setting:`MAILERS` setting *is* defined:

    * ``get_connection()`` with no arguments will return
      :data:`mailers.default`.
    * ``get_connection(...)`` called with only ``fail_silently`` or other
      keyword arguments will create an instance of
      ``MAILERS["default"]`` with any keywords added to the
      default mailer's :setting:`OPTIONS <MAILERS-OPTIONS>`.
    * ``get_connection(backend, ...)`` with a backend import path will raise
      an error.

    If the :setting:`MAILERS` setting is *not* defined:

    * ``get_connection()`` with no arguments will return an instance of the
      email backend specified in :setting:`EMAIL_BACKEND`.
    * If you specify the ``backend`` argument, an instance of that backend will
      be instantiated.
    * If the keyword argument ``fail_silently`` is True, certain
      backend-dependent exceptions during the email sending process will be
      silently ignored.
    * All other keyword arguments are passed directly to the constructor of the
      email backend.

    .. deprecated:: 6.0

        Passing ``fail_silently`` as a positional argument is deprecated.

    .. deprecated:: 6.1

        :func:`!get_connection` is deprecated and will be removed in Django
        7.0. Switch to :data:`mailers[alias] <mailers>`. See
        :ref:`migrating-to-mailers-get-connection` for migration suggestions.

.. _topic-email-backend-api:

Email backend API
-----------------

Instances of an email backend class have the following methods:

* ``open()`` instantiates a long-lived email-sending connection.

* ``close()`` closes the current email-sending connection.

* ``send_messages(email_messages)`` sends a list of :class:`EmailMessage`
  objects. If the connection is not open, this call will implicitly open the
  connection, and close the connection afterward. If the connection is already
  open, it will be left open after mail has been sent.

A backend instance can also be used as a context manager, which will
automatically call ``open()`` and ``close()`` as needed. An example is in
:ref:`topics-sending-multiple-emails`.


Configuring email for development
=================================

There are times when you do not want Django to send emails at
all. For example, while developing a website, you probably don't want
to send out thousands of emails -- but you may want to validate that
emails will be sent to the right people under the right conditions,
and that those emails will contain the correct content.

The easiest way to configure email for local development is to use the
:ref:`console <topic-email-console-backend>` email backend. This backend
redirects all email to ``stdout``, allowing you to inspect the content of mail.

The :ref:`file <topic-email-file-backend>` email backend can also be useful
during development -- this backend dumps the contents of every SMTP connection
to a file that can be inspected at your leisure.

Another approach is to use a mocked SMTP server that receives the emails
locally and displays them to the terminal, but does not actually send
anything. The :pypi:`aiosmtpd` package provides a way to accomplish this:

.. code-block:: shell

    python -m pip install "aiosmtpd >= 1.4.5"

    python -m aiosmtpd -n -l localhost:8025

This command will start a minimal SMTP server listening on port 8025 of
localhost. This server prints to standard output all email headers and the
email body. You then only need to set an SMTP backend's ``"host"`` and
``"port"`` :setting:`OPTIONS <MAILERS-OPTIONS>` accordingly. For a more
detailed discussion of SMTP server options, see the documentation of the
`aiosmtpd`_ module.

.. _aiosmtpd: https://aiosmtpd.readthedocs.io/en/latest/

For information about unit-testing the sending of emails in your application,
see the :ref:`topics-testing-email` section of the testing documentation.
