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

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

Although Python provides a mail sending interface via the :mod:`smtplib`
module, Django provides a couple of light wrappers over it. These wrappers are
provided to make sending email extra quick, to help test email sending during
development, and to provide support for platforms that can't use SMTP.

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"],
        fail_silently=False,
    )

When additional email sending functionality is needed, use
:class:`EmailMessage` or :class:`EmailMultiAlternatives`. 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()

Mail is sent using the SMTP host and port specified in the
:setting:`EMAIL_HOST` and :setting:`EMAIL_PORT` settings. The
:setting:`EMAIL_HOST_USER` and :setting:`EMAIL_HOST_PASSWORD` settings, if
set, are used to authenticate to the SMTP server, and the
:setting:`EMAIL_USE_TLS` and :setting:`EMAIL_USE_SSL` settings control whether
a secure connection is used.

.. 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)

In most cases, you can send email using ``django.core.mail.send_mail()``.

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. When it's ``False``, ``send_mail()`` will raise
  an :exc:`smtplib.SMTPException` if an error occurs. See the :mod:`smtplib`
  docs for a list of possible exceptions, all of which are subclasses of
  :exc:`~smtplib.SMTPException`.
* ``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.

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.

``send_mass_mail()``
====================

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

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), fail_silently=False)

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.

``send_mass_mail()`` vs. ``send_mail()``
----------------------------------------

The main difference between :func:`send_mass_mail` and :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.

``mail_admins()``
=================

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

.. deprecated:: 6.0

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

``mail_managers()``
===================

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

.. deprecated:: 6.0

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

Examples
========

This sends a single email to john@example.com and jane@example.com, with them
both appearing in the "To:"::

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

This sends a message to ``john@example.com`` and ``jane@example.com``, with
them both receiving a separate email::

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

Preventing header injection
===========================

`Header injection`_ is a security exploit in which an attacker inserts extra
email headers to control the "To:" and "From:" in email messages that your
scripts generate.

The Django email functions outlined above all protect against header injection
by forbidding newlines in header values. If any ``subject``, ``from_email`` or
``recipient_list`` contains a newline (in either Unix, Windows or Mac style),
the email function (e.g. :func:`send_mail`) will raise :exc:`ValueError` and,
hence, will not send the email. It's your responsibility to validate all data
before passing it to the email functions.

If a ``message`` contains headers at the start of the string, the headers will
be printed as the first bit of the email message.

Here's an example view that takes a ``subject``, ``message`` and ``from_email``
from the request's POST data, sends that to ``admin@example.com`` and redirects
to "/contact/thanks/" when it's done::

    from django.core.mail import send_mail
    from django.http import HttpResponse, HttpResponseRedirect


    def send_email(request):
        subject = request.POST.get("subject", "")
        message = request.POST.get("message", "")
        from_email = request.POST.get("from_email", "")
        if subject and message and from_email:
            try:
                send_mail(subject, message, from_email, ["admin@example.com"])
            except ValueError:
                return HttpResponse("Invalid header found.")
            return HttpResponseRedirect("/contact/thanks/")
        else:
            # In reality we'd use a form class
            # to get proper validation errors.
            return HttpResponse("Make sure all fields are entered and valid.")


.. versionchanged:: 6.0

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

.. _Header injection: http://www.nyphp.org/phundamentals/8_Preventing-Email-Header-Injection.html

.. _emailmessage-and-smtpconnection:

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>`.

``EmailMessage`` Objects
------------------------

.. 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 legal. 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 in the "Bcc" header 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:: 5.2

          Support for :class:`EmailAttachment` items of ``attachments`` was
          added.

      .. 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.
      Use this parameter if you are sending the :class:`!EmailMessage` via
      :meth:`send` and you want to use the same connection for multiple
      messages. If omitted, a new connection is created when :meth:`send` is
      called. This parameter is ignored when using
      :ref:`send_messages() <topics-sending-multiple-emails>`.

    .. 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)

        Sends the message. If a connection was specified when the email was
        constructed, that connection will be used. Otherwise, an instance of
        the default backend will be instantiated and used. If the keyword
        argument ``fail_silently`` is ``True``, exceptions raised while sending
        the message will be quashed. An empty list of recipients will not raise
        an exception. It will return ``1`` if the message was sent
        successfully, otherwise ``0``.

    .. 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,
        :class:`django.core.mail.backends.smtp.EmailBackend` 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`::

              cid = email.utils.make_msgid()
              inline_image = email.message.MIMEPart()
              inline_image.set_content(
                  image_data_bytes,
                  maintype="image",
                  subtype="png",
                  disposition="inline",
                  cid=f"<{cid}>",
              )
              message.attach(inline_image)
              message.attach_alternative(f'… <img src="cid:${cid}"> …', "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

    .. versionadded:: 5.2

    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.

        .. versionchanged:: 5.2

            In older versions, ``alternatives`` was a list of regular tuples,
            as opposed to :class:`EmailAlternative` named tuples.

    .. 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)

        .. versionadded:: 5.2

        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

    .. versionadded:: 5.2

    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()

.. _topic-email-backends:

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

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

The email backend class has 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.

It can also be used as a context manager, which will automatically call
``open()`` and ``close()`` as needed::

    from django.core import mail

    with mail.get_connection() as connection:
        mail.EmailMessage(
            subject1,
            body1,
            from1,
            [to1],
            connection=connection,
        ).send()
        mail.EmailMessage(
            subject2,
            body2,
            from2,
            [to2],
            connection=connection,
        ).send()

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

The :func:`get_connection` function in ``django.core.mail`` returns an
instance of the email backend that you can use.

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

By default, a call to ``get_connection()`` 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.

The keyword-only ``fail_silently`` argument controls how the backend should
handle errors. If ``fail_silently`` is True, exceptions during the email
sending process will be silently ignored.

All other keyword arguments are passed directly to the constructor of the
email backend.

Django ships with several email sending backends. With the exception of the
SMTP backend (which is the default), these backends are only useful during
testing and development. If you have special email sending requirements, you
can :ref:`write your own email backend <topic-custom-email-backend>`.

.. deprecated:: 6.0

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

.. _topic-email-smtp-backend:

SMTP backend
~~~~~~~~~~~~

.. class:: backends.smtp.EmailBackend(host=None, port=None, username=None, password=None, use_tls=None, fail_silently=False, use_ssl=None, timeout=None, ssl_keyfile=None, ssl_certfile=None, **kwargs)

    This is the default backend. Email will be sent through a SMTP server.

    The value for each argument is retrieved from the matching setting if the
    argument is ``None``:

    * ``host``: :setting:`EMAIL_HOST`
    * ``port``: :setting:`EMAIL_PORT`
    * ``username``: :setting:`EMAIL_HOST_USER`
    * ``password``: :setting:`EMAIL_HOST_PASSWORD`
    * ``use_tls``: :setting:`EMAIL_USE_TLS`
    * ``use_ssl``: :setting:`EMAIL_USE_SSL`
    * ``timeout``: :setting:`EMAIL_TIMEOUT`
    * ``ssl_keyfile``: :setting:`EMAIL_SSL_KEYFILE`
    * ``ssl_certfile``: :setting:`EMAIL_SSL_CERTFILE`

    The SMTP backend is the default configuration inherited by Django. If you
    want to specify it explicitly, put the following in your settings::

        EMAIL_BACKEND = "django.core.mail.backends.smtp.EmailBackend"

    If unspecified, the default ``timeout`` will be the one provided by
    :func:`socket.getdefaulttimeout`, which defaults to ``None`` (no timeout).

.. _topic-email-console-backend:

Console backend
~~~~~~~~~~~~~~~

Instead of sending out real emails the console backend just writes the
emails that would be sent to the standard output. By default, the console
backend writes to ``stdout``. You can use a different stream-like object by
providing the ``stream`` keyword argument when constructing the connection.

To specify this backend, put the following in your settings::

    EMAIL_BACKEND = "django.core.mail.backends.console.EmailBackend"

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

.. _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. The directory to which the files are
written is either taken from the :setting:`EMAIL_FILE_PATH` setting or from the
``file_path`` keyword when creating a connection with :func:`get_connection`.

To specify this backend, put the following in your settings::

    EMAIL_BACKEND = "django.core.mail.backends.filebased.EmailBackend"
    EMAIL_FILE_PATH = "/tmp/app-messages"  # change this to a proper location

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

.. _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.

To specify this backend, put the following in your settings::

  EMAIL_BACKEND = "django.core.mail.backends.locmem.EmailBackend"

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

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

.. _topic-email-dummy-backend:

Dummy backend
~~~~~~~~~~~~~

As the name suggests the dummy backend does nothing with your messages. To
specify this backend, put the following in your settings::

   EMAIL_BACKEND = "django.core.mail.backends.dummy.EmailBackend"

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

.. _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. The :setting:`EMAIL_BACKEND` setting in your settings file is then
the Python import path for your backend class.

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.

.. _topics-sending-multiple-emails:

Sending multiple emails
-----------------------

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 you tell an email backend to reuse a connection.

Firstly, you can use the ``send_messages()`` method on a connection. This takes
a list of :class:`EmailMessage` (or subclass) instances, and sends them all
using that single connection. As a consequence, any :class:`connection
<EmailMessage>` set on an individual message is ignored.

For example, if you have a function called ``get_notification_email()`` 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

    connection = mail.get_connection()  # Use default email connection
    messages = get_notification_email()
    connection.send_messages(messages)

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.

The second approach is to use the ``open()`` and ``close()`` methods on the
email backend to manually control the connection. ``send_messages()`` will not
manually 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

    connection = mail.get_connection()

    # Manually open the connection
    connection.open()

    # Construct an email message that uses the connection
    email1 = mail.EmailMessage(
        "Hello",
        "Body goes here",
        "from@example.com",
        ["to1@example.com"],
        connection=connection,
    )
    email1.send()  # Send the email

    # Construct two more messages
    email2 = mail.EmailMessage(
        "Hello",
        "Body goes here",
        "from@example.com",
        ["to2@example.com"],
    )
    email3 = mail.EmailMessage(
        "Hello",
        "Body goes here",
        "from@example.com",
        ["to3@example.com"],
    )

    # Send the two emails in a single call -
    connection.send_messages([email2, email3])
    # The connection was already open so send_messages() doesn't close it.
    # We need to manually close the connection.
    connection.close()


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 "dumb" 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 the :setting:`EMAIL_HOST` and
:setting:`EMAIL_PORT` 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.
