django-inbound-email 0.1.4

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An inbound email handler for Django.

Current Status

A basic working implementation, with SendGrid backend.

What?

A Django app to make it easy to receive inbound emails from users via a hosted transactional email service (e.g. SendGrid, Postmark, Mandrill, etc.)

Why?

If your project accepts inbound emails, you are probably using one of the big transactional email providers.

These services all provide a mechanism for receiving inbound emails which involves them (the service) parsing the inbound email and then posting the contents to an HTTP endpoint in your project. This is a great service, but it can often be fiddly to integrate into your app and it reinforces service lock-in, as each service’s callback is slightly different.

There is also a significant SMTP-HTTP ‘impedance mismatch’. You send emails through Django’s (SMTP) mail library, which provides the EmailMessage and EmailMultiAlternative objects, but you receive emails as an HTTP POST. Wouldn’t it be nice if you could both send and receive Django objects?

This app converts the incoming HttpRequest back into an EmailMultiAlternatives object, and fires a signal that sends both the new object, and the original request object. You simply have to listen for this signal, and process the email as your application requires.

The mail parser handles non-UTF-8 character sets (so those pesky PC Outlook emails don’t come through all garbled), and file attachments.

How?

Although this is Django app, it contains (for now) no models. Its principle component is a single view function that does the parsing. There is a single configuration setting - INBOUND_EMAIL_PROVIDER, which must be one of the supported backends (default will be ‘SendGrid’ as that’s what we use). This setting is expected to be available to the app from django.conf.settings, and the app will raise an error if it does not exist.

The default URL for inbound emails is simply ‘/inbound/’.

The flow through the app is very simple:

1. The app view function receive_inbound is called when a new email POST is received from your service provider.

2. This function looks up the INBOUND_EMAIL_PROVIDER, loads the appropriate backend, and parses the request.POST contents out into a new django.core.mail.EmailMultiAlternatives object.

3. The email_received signal is fired, and the new EmailMultiAlternatives instance is passed, along with the original HttpRequest (in case there’s any special handling that you require - e.g. DKIM / SPF info, if your provider passes that along).

Your main concern, after installing and configuring the app, is handling the email_received signal:

# This snippet goes somewhere inside your project,
# wherever you need to react to incoming emails.
import logging
from django_inbound.signals import email_received

def on_email_received(sender, **kwargs):
    """Handle inbound emails."""
    email = kwargs.pop('email')
    request = kwargs.pop('request')

    # your code goes here - save the email, respond to it, etc.
    logging.debug(
        "New email received from %s: %s",
        email.from_email,
        email.subject
    )

# pass dispatch_uid to prevent duplicates:
# https://docs.djangoproject.com/en/dev/topics/signals/
email_received.connect(on_email_received, dispatch_uid="something_unique")

Installation

For use as the app in Django project, use pip:

$ pip install django-inbound-email

For hacking on the project, pull from Git:

$ git pull [e-mail]:yunojuno/django-inbound-email.git
$ cd django-inbound-email
django-inbound-email$
# use virtualenvwrapper, and install Django to allow tests to run
django-inbound-email$ mkvirtualenv django-inbound-email
(django-inbound-email) django-inbound-email$ pip install django

Tests

There is a test django project, test_app that is used to run the tests.

(django-inbound-email) django-inbound-email$ python manage.py test

Configuration

• Install the app

• Add the app to INSTALLED_APPS

• Add INBOUND_EMAIL_PARSER setting

• Update your provider configuration to point to app URL

# the fully-qualified path to the provider's backend parser
INBOUND_EMAIL_PARSER = 'django_inbound_email.backends.sendgrid.SendGridRequestParser'

# if True (default=False) then log the contents of each inbound request
INBOUND_EMAIL_LOG_REQUESTS = True

# if True (default=True) then always return HTTP status of 200 (may be required by provider)
INBOUND_EMAIL_RESPONSE_200 = True

# add the app to Django's INSTALL_APPS setting
INSTALLED_APPS = (
    # other apps
    # ...
    'django_inbound_email',
)

Features

Things it will do:

• Parse HTTP requests into EmailMultiAlternatives objects

• Pluggable backends (SendGrid only on launch)

• Handle character encodings properly

• Handle attachments

Things it (probably) won’t do:

• Handle email reply parsing - use https://github.com/zapier/email-reply-parser

Progress to date

This doesn’t exist yet, as we are waiting till we finish our current workload before building this.

All the functionality exists within our own project (www.yunojuno.com), it just needs extracting into a separate app, a setup.py, registration with PyPI, and so on… It’ll land in May. Possibly.