A Django email multi backend

This project aims to help with this situations:

- e-mail provider/backends A/B testing (eg. which provider gives you better deliverability?)
- e-mail provider migration (eg. you can use weights to ramp up traffic)
- routing emails to backends

How it works:

When using this email backend e-mails are routed to a list of compatible backends.
By default all backends are used, if needed it is possible to select / exclude backends (eg. exclude email with header X). Once the selection is done the backend chooses one of them via a random weighted choice.

EMAIL_BACKENDS
A dictonary that defines the available backends

EMAIL_BACKENDS_WEIGHTS
A tuple of (backend_name, weight) that defines the weights used to distribute the emails among backends. This setting is optional, when not defined emails are going to be distributed evenly across the backends

EMAIL_BACKENDS_CONDITIONS A dictonary that maps a backend to a list of conditions that needs to be

Example settings:

EMAIL_BACKENDS = {
    'mailjet': {
        'backend': 'django.core.mail.backends.smtp.EmailBackend',
        'host': 'in.mailjet.com',
        'port': '25',
        'username': 'username',
        'password': 'secret',
        'use_tls': False
    },
    'mandarill': {
        'backend': 'django.core.mail.backends.smtp.EmailBackend',
        'host': 'in.mandarill.com',
        'port': '587',
        'username': 'user',
        'password': 'pass',
        'use_tls': True
    },
}

EMAIL_BACKENDS_WEIGHTS = (
    ('mailjet', 7), ('mandarill', 3)
)

EMAIL_BACKENDS_CONDITIONS = {
    'mandarill': ('django_email_multibackend.conditions.ExcludeMailByHeader', {'header': ('X-MAIL-TYPE', 'non-transactional')})
}

EMAIL_BACKEND = 'django_email_multibackend.backends.EmailMultiServerBackend'

With this setting 70% of emails will be sent via mailjet and 30% via mandrill; the mandrill backend will never be used to send emails with header X-MAIL-TYPE=non-transactional

Routing conditions must be callables classes (or callable factories), accept one argument (the email message is sent at routing time) and finally return a boolean see django_email_multibackend.conditions.BaseCondition and other implementations.

Conditions are initialised with the options provided in the EMAIL_BACKENDS_CONDITIONS settings and then called with the email message to send as parameter.

You can run tests via setuptools (it will install the requirements to run the tests)

python setup.py test

if you want to skip the setuptools

python runtests.py

or just use py.test directly

DJANGO_SETTINGS_MODULE='django_email_multibackend.test_settings' py.test django_email_multibackend

Every build of the project is built on Travis CI against python 2.6 / 2.7 / 3.2 / 3.3