django-post-office 1.0.0

A Django app to monitor and send mail asynchronously, complete with template support.

==================
Django Post Office
==================

Django Post Office is a simple app to send and manage your emails in Django.
Some awesome features are:

* Allows you to send email asynchronously
* Supports HTML email
* Supports database based email templates
* Built in scheduling support
* Works well with task queues like `RQ <http://python-rq.org>`_ or `Celery <http://www.celeryproject.org>`_
* Uses multiprocessing to send a large number of emails in parallel


Dependencies
============

* `django >= 1.4 <http://djangoproject.com/>`_
* `django-jsonfield <https://github.com/bradjasper/django-jsonfield>`_


Installation
============

|Build Status|


* Install from PyPI (or you `manually download from PyPI <http://pypi.python.org/pypi/django-post_office>`_)::

pip install django-post_office

* Add ``post_office`` to your INSTALLED_APPS in django's ``settings.py``:

.. code-block:: python

INSTALLED_APPS = (
# other apps
"post_office",
)

* Run ``syncdb``::

python manage.py syncdb

* Set ``post_office.EmailBackend`` as your ``EMAIL_BACKEND`` in django's ``settings.py``::

EMAIL_BACKEND = 'post_office.EmailBackend'


Quickstart
==========

Send a simple email is really easy:

.. code-block:: python

from post_office import mail

mail.send(
'[e-mail]', # List of email addresses also accepted
'[e-mail]',
subject='My email',
message='Hi there!',
html_message='Hi <strong>there</strong>!',
)


If you want to use templates, ensure that Django's admin interface is enabled. Create an
``EmailTemplate`` instance via ``admin`` and do the following:

.. code-block:: python

from post_office import mail

mail.send(
'[e-mail]', # List of email addresses also accepted
'[e-mail]',
template='welcome_email', # Could be an EmailTemplate instance or name
context={'foo': 'bar'},
)

The above command will put your email on the queue so you can use the
command in your webapp without slowing down the request/response cycle too much.
To actually send them out, run ``python manage.py send_queued_mail``.
You can schedule this management command to run regularly via cron::

* * * * * (/usr/bin/python manage.py send_queued_mail >> send_mail.log 2>&1)


Usage
=====

mail.send()
-----------

``mail.send`` is the most important function in this library, it takes these
arguments:

+-------------------+----------+-------------------------------------------------+
| Argument | Required | Description |
+-------------------+----------+-------------------------------------------------+
| recipients | Yes | list of recipient email addresses |
+-------------------+----------+-------------------------------------------------+
| sender | No | Defaults to ``settings.DEFAULT_FROM_EMAIL``, |
| | | display name is allowed (``John <[e-mail]>``) |
+-------------------+----------+-------------------------------------------------+
| subject | No | Email subject (if ``template`` is not specified)|
+-------------------+----------+-------------------------------------------------+
| message | No | Email content (if ``template`` is not specified)|
+-------------------+----------+-------------------------------------------------+
| html_message | No | HTML content (if ``template`` is not specified) |
+-------------------+----------+-------------------------------------------------+
| template | No | ``EmailTemplate`` instance or name |
+-------------------+----------+-------------------------------------------------+
| cc | No | list emails, will appear in ``cc`` field |
+-------------------+----------+-------------------------------------------------+
| bcc | No | list of emails, will appear in `bcc` field |
+-------------------+----------+-------------------------------------------------+
| attachments | No | Email attachments - A dictionary where the keys |
| | | are the filenames and the values are either: |
| | | |
| | | * files |
| | | * file-like objects |
| | | * full path of the file |
+-------------------+----------+-------------------------------------------------+
| context | No | A dictionary, used to render templated email |
+-------------------+----------+-------------------------------------------------+
| headers | No | A dictionary of extra headers on the message |
+-------------------+----------+-------------------------------------------------+
| scheduled_time | No | A date/datetime object indicating when the email|
| | | should be sent |
+-------------------+----------+-------------------------------------------------+
| priority | No | ``high``, ``medium``, ``low`` or ``now`` |
| | | (send_immediately) |
+-------------------+----------+-------------------------------------------------+
| render_on_delivery| No | Setting this to ``True`` causes email to be |
| | | lazily rendered during delivery. ``template`` |
| | | is required when ``render_on_delivery`` is True.|
| | | This way content is never stored in the DB. |
| | | May result in significat space savings. |
+-------------------+----------+-------------------------------------------------+


Here are a few examples.

If you just want to send out emails without using database templates. You can
call the ``send`` command without the ``template`` argument.

.. code-block:: python

from post_office import mail

mail.send(
['[e-mail]'],
'[e-mail]',
subject='Welcome!',
message='Welcome home, {{ name }}!',
html_message='Welcome home, <b>{{ name }}</b>!',
headers={'Reply-to': '[e-mail]'},
scheduled_time=date(2014, 1, 1),
context={'name': 'Alice'},
)

``post_office`` is also task queue friendly. Passing ``now`` as priority into
``send_mail`` will deliver the email right away (instead of queuing it),
regardless of how many emails you have in your queue:

.. code-block:: python

from post_office import mail

mail.send(
['[e-mail]'],
'[e-mail]',
template='welcome_email',
context={'foo': 'bar'},
priority='now',
)

This is useful if you already use something like `django-rq <https://github.com/ui/django-rq>`_
to send emails asynchronously and only need to store email related activities and logs.

If you want to send an email with attachments:

.. code-block:: python

from django.core.files.base import ContentFile
from post_office import mail

mail.send(
['[e-mail]'],
'[e-mail]',
template='welcome_email',
context={'foo': 'bar'},
priority='now',
attachments={
'attachment1.doc', '/path/to/file/file1.doc',
'attachment2.txt', ContentFile('file content'),
}
)

Template Tags and Variables
---------------------------

``post-office`` supports Django's template tags and variables.
For example, if you put "Hello, {{ name }}" in the subject line and pass in
``{'name': 'Alice'}`` as context, you will get "Hello, Alice" as subject:

.. code-block:: python

from post_office.models import EmailTemplate
from post_office import mail

EmailTemplate.objects.create(
name='morning_greeting',
subject='Morning, {{ name|capfirst }}',
content='Hi {{ name }}, how are you feeling today?',
html_content='Hi <strong>{{ name }}</strong>, how are you feeling today?',
)

mail.send(
['[e-mail]'],
'[e-mail]',
template='morning_greeting',
context={'name': 'alice'},
)

# This will create an email with the following content:
subject = 'Morning, Alice',
content = 'Hi alice, how are you feeling today?'
content = 'Hi <strong>alice</strong>, how are you feeling today?'


Custom Email Backends
---------------------

By default, ``post_office`` uses django's SMTP ``EmailBackend``. If you want to
use a different backend, you can do so by changing ``EMAIL_BACKEND``.

For example if you want to use `django-ses <https://github.com/hmarr/django-ses>`_::

POST_OFFICE = {
'EMAIL_BACKEND': 'django_ses.SESBackend'
}


Management Commands
-------------------

* ``send_queued_mail`` - send queued emails, those aren't successfully sent
will be marked as ``failed``. Accepts the following arguments:

+---------------------------+-------------------------------------------------+
| Argument | Description |
+---------------------------+-------------------------------------------------+
| ``--processes`` or ``-p`` | Number of parallel processes to send email. |
| | Defaults to 1 |
+---------------------------+---------+---------------------------------------+
| ``--lockfile`` or ``-L`` | Full path to file used as lock file. Defaults to|
| | ``/tmp/post_office.lock`` |
+---------------------------+-------------------------------------------------+


* ``cleanup_mail`` - delete all emails created before an X number of days
(defaults to 90).

You may want to set these up via cron to run regularly::

* * * * * (cd $PROJECT; python manage.py send_queued_mail --processes=1 >> $PROJECT/cron_mail.log 2>&1)
0 1 * * * (cd $PROJECT; python manage.py cleanup_mail --days=30 >> $PROJECT/cron_mail_cleanup.log 2>&1)

Settings
========
This section outlines all the settings and configurations that you can put
in Django's ``settings.py`` to fine tune ``post-office``'s behavior.

Batch Size
----------

If you may want to limit the number of emails sent in a batch (sometimes useful
in a low memory environment), use the ``BATCH_SIZE`` argument to limit the
number of queued emails fetched in one batch.

.. code-block:: python

# Put this in settings.py
POST_OFFICE = {
'BATCH_SIZE': 5000
}

Default Priority
----------------

The default priority for emails is ``medium``, but this can be altered by
setting ``DEFAULT_PRIORITY``. Integration with asynchronous email backends
(e.g. based on Celery) becomes trivial when set to ``now``.

.. code-block:: python

# Put this in settings.py
POST_OFFICE = {
'DEFAULT_PRIORITY': 'now'
}

Log Level
---------

The default log level is 2 (logs both successful and failed deliveries)
This behavior can be changed by setting ``LOG_LEVEL``.

.. code-block:: python

# Put this in settings.py
POST_OFFICE = {
'LOG_LEVEL': 1 # Log only failed deliveries
}

The different options are:
* ``0`` logs nothing
* ``1`` logs only failed deliveries
* ``2`` logs everything (both successful and failed delivery attempts)

Context Field Serializer
------------------------

If you need to store complex Python objects for deferred rendering
(i.e. setting ``render_on_delivery=True``), you can specify your own context
field class to store context variables. For example if you want to use
`django-picklefield <https://github.com/gintas/django-picklefield/tree/master/src/picklefield>`_:

.. code-block:: python

# Put this in settings.py
POST_OFFICE = {
'CONTEXT_FIELD_CLASS': 'picklefield.fields.PickledObjectField'
}

``CONTEXT_FIELD_CLASS`` defaults to ``jsonfield.JSONField``.

Logging
-------

You can configure ``post-office``'s logging from Django's ``settings.py``. For
example:

.. code-block:: python

LOGGING = {
"version": 1,
"disable_existing_loggers": False,
"formatters": {
"post_office": {
"format": "[%(levelname)s]%(asctime)s PID %(process)d: %(message)s",
"datefmt": "%d-%m-%Y %H:%M:%S",
},
},
"handlers": {
"post_office": {
"level": "DEBUG",
"class": "logging.StreamHandler",
"formatter": "post_office"
},
# If you use sentry for logging
'sentry': {
'level': 'ERROR',
'class': 'raven.contrib.django.handlers.SentryHandler',
},
},
'loggers': {
"post_office": {
"handlers": ["post_office", "sentry"],
"level": "INFO"
},
},
}

Performance
===========

Caching
-------

if Django's caching mechanism is configured, ``post_office`` will cache
``EmailTemplate`` instances . If for some reason you want to disable caching,
set ``POST_OFFICE_CACHE`` to ``False`` in ``settings.py``:

.. code-block:: python

## All cache key will be prefixed by post_office:template:
## To turn OFF caching, you need to explicitly set POST_OFFICE_CACHE to False in settings
POST_OFFICE_CACHE = False

## Optional: to use a non default cache backend, add a "post_office" entry in CACHES
CACHES = {
'post_office': {
'BACKEND': 'django.core.cache.backends.memcached.PyLibMCCache',
'LOCATION': '127.0.0.1:11211',
}
}


send_many()
-----------

``send_many()`` is much more performant (generates less database queries) when
sending a large number of emails. ``send_many()`` is almost identical to ``mail.send()``,
with the exception that it accepts a list of keyword arguments that you'd
usually pass into ``mail.send()``:

.. code-block:: python

from post_office import mail

first_email = {
'sender': '[e-mail]',
'recipients': ['[e-mail]'],
'subject': 'Hi!',
'message': 'Hi Alice!'
}
second_email = {
'sender': '[e-mail]',
'recipients': ['[e-mail]'],
'subject': 'Hi!',
'message': 'Hi Bob!'
}
kwargs_list = [first_email, second_email]

mail.send_many(kwargs_list)

Attachments are not supported with ``mail.send_many()``.


Running Tests
=============

To run the test suite::

`which django-admin.py` test post_office --settings=post_office.test_settings --pythonpath=.


Changelog
=========

Version 1.0.0 (Not yet released)
--------------------------------
* **IMPORTANT**: in older versions, passing multiple ``recipients`` into
``mail.send()`` will create multiple emails, each addressed to one recipient.
Starting from ``1.0.0``, only one email with multiple recipients will be created.
* Added ``LOG_LEVEL`` setting.
* ``mail.send()`` now supports ``cc`` and ``bcc``.
Thanks Ștefan Daniel Mihăilă (@stefan-mihaila)!
* Improvements to ``admin`` interface; you can now easily requeue multiple emails.
* ``Log`` model now stores the type of exception caught during sending.
* ``send_templated_mail`` command is now deprecated.
* Added ``EMAIL_BACKEND`` setting to the new dictionary-styled settings.

Version 0.8.4
-------------
* ``send_queued_mail`` now accepts an extra ``--log-level`` argument.
* ``mail.send()`` now accepts an extra ``log_level`` argument.
* Drop unused/low cardinality indexes to free up RAM on large tables.

Version 0.8.3
-------------
* ``send_queued_mail`` now accepts ``--lockfile`` argument.
* Lockfile implementation has been modified to use symlink, which is an atomic operation
across platforms.

Version 0.8.2
-------------
* Added ``CONTEXT_FIELD_CLASS`` setting to allow other kinds of context field serializers.

Version 0.8.1
-------------
* Fixed a bug that causes context to be saved when ``render_on_delivery`` is False

Version 0.8.0
-------------
* Added a new setting ``DEFAULT_PRIORITY`` to set the default priority for emails.
Thanks Maik Hoepfel (@maikhoepfel)!
* ``mail.send()`` gains a ``render_on_delivery`` argument that may potentially
result in significant storage space savings.
* Uses a new locking mechanism that can detect zombie PID files.

Version 0.7.2
-------------
* Made a few tweaks that makes ``post_office`` much more efficient on systems with
large number of rows (millions).

Version 0.7.1
-------------
* Python 3 compatibility fix.

Version 0.7.0
-------------
* Added support for sending attachments. Thanks @yprez!
* Added ``description`` field to ``EmailTemplate`` model to store human readable
description of templates. Thanks Michael P. Jung (@bikeshedder)!
* Changed ``django-jsonfield`` dependency to ``jsonfield`` for Python 3 support reasons.
* Minor bug fixes.

Version 0.6.0
-------------
* Support for Python 3!
* Added mail.send_many() that's much more performant when sending
a large number emails

Version 0.5.2
-------------
* Added logging
* Added BATCH_SIZE configuration option

Version 0.5.1
-------------
* Fixes various multiprocessing bugs

Version 0.5.0
-------------
* Email sending can now be parallelized using multiple processes (multiprocessing)
* Email templates are now validated before save
* Fixed a bug where custom headers aren't properly sent

Version 0.4.0
-------------
* Added support for sending emails with custom headers (you'll need to run
South when upgrading from earlier versions)
* Added support for scheduled email sending
* Backend now properly persist emails with HTML alternatives

Version 0.3.1
-------------
* **IMPORTANT**: ``mail.send`` now expects recipient email addresses as the first
argument. This change is to allow optional ``sender`` parameter which defaults
to ``settings.DEFAULT_FROM_EMAIL``
* Fixed a bug where all emails sent from ``mail.send`` have medium priority

Version 0.3.0
-------------
* **IMPORTANT**: added South migration. If you use South and had post-office
installed before 0.3.0, you may need to manually resolve migration conflicts
* Allow unicode messages to be displayed in ``/admin``
* Introduced a new ``mail.send`` function that provides a nicer API to send emails
* ``created`` fields now use ``auto_now_add``
* ``last_updated`` fields now use ``auto_now``

Version 0.2.1
-------------
* Fixed typo in ``admin.py``

Version 0.2
-----------
* Allows sending emails via database backed templates

Version 0.1.5
-------------
* Errors when opening connection in ``Email.dispatch`` method are now logged


.. |Build Status| image:: https://travis-ci.org/ui/django-post_office.png?branch=master
:target: https://travis-ci.org/ui/django-post_office