==============
Sending e-mail
==============

Although Python makes sending e-mail relatively easy via the `smtplib library`_,
Django provides a couple of light wrappers over it, to make sending e-mail
extra quick.

The code lives in a single module: ``django.core.mail``.

.. _smtplib library: http://www.python.org/doc/current/lib/module-smtplib.html

Quick example
=============

In two lines::

    from django.core.mail import send_mail

    send_mail('Subject here', 'Here is the message.', 'from@example.com',
        ['to@example.com'], fail_silently=False)

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

.. note::

    The character set of e-mail sent with ``django.core.mail`` will be set to
    the value of your `DEFAULT_CHARSET setting`_.

.. _DEFAULT_CHARSET setting: ../settings/#default-charset
.. _EMAIL_HOST: ../settings/#email-host
.. _EMAIL_PORT: ../settings/#email-port
.. _EMAIL_HOST_USER: ../settings/#email-host-user
.. _EMAIL_HOST_PASSWORD: ../settings/#email-host-password
.. _EMAIL_USE_TLS: ../settings/#email-use-tls

send_mail()
===========

The simplest way to send e-mail is using the function
``django.core.mail.send_mail()``. Here's its definition::

    send_mail(subject, message, from_email, recipient_list,
        fail_silently=False, auth_user=None,
        auth_password=None)

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

    * ``subject``: A string.
    * ``message``: A string.
    * ``from_email``: A string.
    * ``recipient_list``: A list of strings, each an e-mail address. Each
      member of ``recipient_list`` will see the other recipients in the "To:"
      field of the e-mail message.
    * ``fail_silently``: A boolean. If it's ``False``, ``send_mail`` will raise
      an ``smtplib.SMTPException``. See the `smtplib docs`_ for a list of
      possible exceptions, all of which are subclasses of ``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
      ``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
      ``EMAIL_HOST_PASSWORD`` setting.

.. _smtplib docs: http://www.python.org/doc/current/lib/module-smtplib.html

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

``django.core.mail.send_mass_mail()`` is intended to handle mass e-mailing.
Here's the definition::

    send_mass_mail(datatuple, fail_silently=False,
        auth_user=None, auth_password=None):

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

    (subject, message, from_email, recipient_list)

``fail_silently``, ``auth_user`` and ``auth_password`` have the same functions
as in ``send_mail()``.

Each separate element of ``datatuple`` results in a separate e-mail message.
As in ``send_mail()``, recipients in the same ``recipient_list`` will all see
the other addresses in the e-mail messages's "To:" field.

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

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

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

``django.core.mail.mail_admins()`` is a shortcut for sending an e-mail to the
site admins, as defined in the `ADMINS setting`_. Here's the definition::

    mail_admins(subject, message, fail_silently=False)

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

The "From:" header of the e-mail will be the value of the `SERVER_EMAIL setting`_.

This method exists for convenience and readability.

.. _ADMINS setting: ../settings/#admins
.. _EMAIL_SUBJECT_PREFIX setting: ../settings/#email-subject-prefix
.. _SERVER_EMAIL setting: ../settings/#server-email

mail_managers() function
========================

``django.core.mail.mail_managers()`` is just like ``mail_admins()``, except it
sends an e-mail to the site managers, as defined in the `MANAGERS setting`_.
Here's the definition::

    mail_managers(subject, message, fail_silently=False)

.. _MANAGERS setting: ../settings/#managers

Examples
========

This sends a single e-mail 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 e-mail::

    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
e-mail headers to control the "To:" and "From:" in e-mail messages that your
scripts generate.

The Django e-mail 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 e-mail function (e.g. ``send_mail()``) will raise
``django.core.mail.BadHeaderError`` (a subclass of ``ValueError``) and, hence,
will not send the e-mail. It's your responsibility to validate all data before
passing it to the e-mail functions.

If a ``message`` contains headers at the start of the string, the headers will
simply be printed as the first bit of the e-mail 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, BadHeaderError

    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 BadHeaderError:
                return HttpResponse('Invalid header found.')
            return HttpResponseRedirect('/contact/thanks/')
        else:
            # In reality we'd use a manipulator
            # to get proper validation errors.
            return HttpResponse('Make sure all fields are entered and valid.')

.. _Header injection: http://securephp.damonkohler.com/index.php/Email_Injection

The EmailMessage and SMTPConnection classes
===========================================

**New in Django development version**

Django's ``send_mail()`` and ``send_mass_mail()`` functions are actually thin
wrappers that make use of the ``EmailMessage`` and ``SMTPConnection`` classes
in ``django.core.mail``.  If you ever need to customize the way Django sends
e-mail, you can subclass these two classes to suit your needs.

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

In general, ``EmailMessage`` is responsible for creating the e-mail message
itself. ``SMTPConnection`` is responsible for the network connection side of
the operation. This means you can reuse the same connection (an
``SMTPConnection`` instance) for multiple messages.

The ``EmailMessage`` class is initialized as follows::

    email = EmailMessage(subject, body, from_email, to, bcc, connection)

All of these parameters are optional. If ``from_email`` is omitted, the value
from ``settings.DEFAULT_FROM_EMAIL`` is used. Both the ``to`` and ``bcc``
parameters are lists of addresses, as strings.

For example::

    email = EmailMessage('Hello', 'Body goes here', 'from@example.com',
                ['to1@example.com', 'to2@example.com'],
                ['bcc@example.com'])

The class has the following methods:

    * ``send()`` sends the message, using either the connection that is
      specified in the ``connection`` attribute, or creating a new connection
      if none already exists.

    * ``message()`` constructs a ``django.core.mail.SafeMIMEText`` object (a
      sub-class of Python's ``email.MIMEText.MIMEText`` class) holding the
      message to be sent. If you ever need to extend the `EmailMessage` class,
      you'll probably want to override this method to put the content you wish
      into the MIME object.

    * ``recipients()`` returns a list of all the recipients of the message,
      whether they're recorded in the ``to`` or ``bcc`` attributes. This is
      another method you might need to override when sub-classing, 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.

The ``SMTPConnection`` class is initialized with the host, port, username and
password for the SMTP server. If you don't specify one or more of those
options, they are read from your settings file.

If you're sending lots of messages at once, the ``send_messages()`` method of
the ``SMTPConnection`` class is useful. It takes a list of ``EmailMessage``
instances (or subclasses) and sends them over a single connection. For example,
if you have a function called ``get_notification_email()`` that returns a
list of ``EmailMessage`` objects representing some periodic e-mail you wish to
send out, you could send this with::

    connection = SMTPConnection()   # Use default settings for connection
    messages = get_notification_email()
    connection.send_messages(messages)
