django-mailer: A Python repository from ebdavison

Django Mailer

django-mailer

django-mailer is a reusable Django app for queuing the sending of email. It works by storing email in the database for later sending. The main reason for doing this is that for many apps, the database will be much more reliable and faster than other email sending backends which require 3rd party services e.g. SMTP or an HTTP API. By storing and sending later, we can return succeed immediately, and then attempt actual email sending in the background, with retries if needed.

An additional use case is that if you are storing the mail in the same database as your normal application, the database call can participate in any ongoing transaction - that is, if the database transaction is rolled back, the email sending will also be rolled back. (In some cases this behaviour might not be desirable, so be careful).

Keep in mind that file attachments are also temporarily stored in the database, which means if you are sending files larger than several hundred KB in size, you are likely to run into database limitations on how large your query can be. If this happens, you'll either need to fall back to using Django's default mail backend, or increase your database limits (a procedure that depends on which database you are using).

django-mailer was developed as part of the Pinax ecosystem but is just a Django app and can be used independently of other Pinax apps.

Requirements

Django >= 1.11
Databases: django-mailer supports all databases that Django supports, with the following notes:
- SQLite: you may experience 'database is locked' errors if the send_mail command runs when anything else is attempting to put items on the queue. For this reason SQLite is not recommended for use with django-mailer.

Getting Started

Simple usage instructions:

In settings.py:

INSTALLED_APPS = [
    ...
    "mailer",
    ...
]

EMAIL_BACKEND = "mailer.backend.DbBackend"

Run database migrations to set up the needed database tables.

Then send email in the normal way, as per the Django email docs, and they will be added to the queue.

To actually send the messages on the queue, add this to a cron job file or equivalent:

*       * * * * (/path/to/your/python /path/to/your/manage.py send_mail >> ~/cron_mail.log 2>&1)
0,20,40 * * * * (/path/to/your/python /path/to/your/manage.py retry_deferred >> ~/cron_mail_deferred.log 2>&1)

To prevent from the database filling up with the message log, you should clean it up every once in a while.

To remove successful log entries older than a week, add this to a cron job file or equivalent:

0 0 * * * (/path/to/your/python /path/to/your/manage.py purge_mail_log 7 >> ~/cron_mail_purge.log 2>&1)

Use the -r failure option to remove only failed log entries instead, or -r all to remove them all.

Note that the send_mail cronjob can only run at a maximum frequency of once each minute. If a maximum delay of 60 seconds between creating an email and sending it is too much, an alternative is available.

Using ./manage.py runmailer a long running process is started that will check the database for new emails each MAILER_EMPTY_QUEUE_SLEEP (default: 30 seconds).

Documentation and support

See usage.rst in the docs for more advanced use cases. The Pinax documentation is available at http://pinaxproject.com/pinax/.

This is an Open Source project maintained by volunteers, and outside this documentation the maintainers do not offer other support. For cases where you have found a bug you can file a GitHub issue. In case of any questions we recommend you join the Pinax Slack team and ping the Pinax team there instead of creating an issue on GitHub. You may also be able to get help on other programming sites like Stack Overflow.

Contribute

See CONTRIBUTING.rst for information about contributing patches to django-mailer.

See this blog post including a video, or our How to Contribute section for an overview on how contributing to Pinax works. For concrete contribution ideas, please see our Ways to Contribute/What We Need Help With section.

We also highly recommend reading our Open Source and Self-Care blog post.

Code of Conduct

In order to foster a kind, inclusive, and harassment-free community, the Pinax Project has a code of conduct. We ask you to treat everyone as a smart human programmer that shares an interest in Python, Django, and Pinax with you.

Pinax Project Blog and Twitter

For updates and news regarding the Pinax Project, please follow us on Twitter at @pinaxproject and check out our blog.

ebdavison/django-mailer