Django Debug Toolbar - Mail Panel

Testing and debugging e-mail while developing a Django app has never been pleasant. Sending e-mail to a file-based backend requires a user to click through obtusely-named files and does not provide a way to preview rendered HTML. Sending e-mail to a valid mailbox incurs a delay as the message is processed though a mail server, and clutters a developer's inbox.

The mail panel attempts to address these problems by providing a way to preview emails within the browser using django-debug-toolbar.

This mail panel is released under the Apache license. If you like it, please consider contributing!

Special thanks to @ShawnMilo for the code review.

Installation

To install the mail panel, first install this package with pip install django-mail-panel. Then add the mail_panel app after debug_toolbarto the INSTALLED_APPS setting:

INSTALLED_APPS = (
    ...
    'debug_toolbar',
    'mail_panel',
)

and add the panel DEBUG_TOOLBAR_PANELS:

DEBUG_TOOLBAR_PANELS = (
    ...
    'mail_panel.panels.MailToolbarPanel',
)

Collect static and you'll be good to go.

./manage.py collectstatic

Configuration

After installation, you now need to redirect mail to the mail toolbar. Change your email backend to the following:

EMAIL_BACKEND = 'mail_panel.backend.MailToolbarBackend'

Important: This plugin uses Django's cache backend to store messages. If you are using DummyCache, the mail panel will use a local memory cache, and will reset messages when the server is restarted.

[Optional] By default, mail toolbar stores messages for one day before removing them from cache. You can change this with the following setting:

MAIL_TOOLBAR_TTL = 86400  # 1 Day

[Optional] If you use the DEBUG_TOOLBAR_PANELS to custom order your panels:

    DEBUG_TOOLBAR_PANELS = [
        "debug_toolbar.panels.history.HistoryPanel",
        "debug_toolbar.panels.versions.VersionsPanel",
        "debug_toolbar.panels.timer.TimerPanel",
        "debug_toolbar.panels.settings.SettingsPanel",
        "debug_toolbar.panels.headers.HeadersPanel",
        "debug_toolbar.panels.request.RequestPanel",
        "debug_toolbar.panels.sql.SQLPanel",
        "debug_toolbar.panels.staticfiles.StaticFilesPanel",
        "debug_toolbar.panels.templates.TemplatesPanel",
        "debug_toolbar.panels.cache.CachePanel",
        "debug_toolbar.panels.signals.SignalsPanel",
        "debug_toolbar.panels.logging.LoggingPanel",
        "debug_toolbar.panels.redirects.RedirectsPanel",
        "debug_toolbar.panels.profiling.ProfilingPanel",
        "mail_panel.panels.MailToolbarPanel",  # reposition to desired location
    ]

Testing

To preview emails sent from your test suite, add the email backend override to your tests with the following:

from django.test.utils import override_settings

@override_settings(EMAIL_BACKEND='mail_panel.backend.MailToolbarBackend')
def test_send_email(self):
    # your code here

The backend works similarly to the standard email backend and code should not need to be reworked when using the MailToolbarBackend.

from django.core import mail

original_outbox = len(mail.outbox)
# Send mail ...
assert(len(mail.outbox) == original_outbox + 1)

Shameless Plugs

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