Fast Django development email backend (socket.getfqdn() slowness)

1fast_email_backend.py

from django.core.mail.message import make_msgid


class FastMailBackendMixin:
    """Work around slow development email backend due to slow socket.getfqdn() call.

    This simply uses "example.com" instead of your local machine's hostname.
    """
    def send_messages(self, messages):
        for message in messages:
            if 'message-id' not in message.extra_headers:
                message.extra_headers['Message-ID'] = make_msgid(domain='example.com')
        return super().send_messages(messages)

2dev_example.py

from django.core.mail.backends.locmem import EmailBackend

class FastEmailBackend(FastMailBackendMixin, EmailBackend):
    pass

 
# settings.py:

EMAIL_BACKEND = 'yourapp.fast_email_backend.FastEmailBackend'

3unittest_example.py

from django.test import TestCase, override_settings

@override_settings(EMAIL_BACKEND='yourapp.fast_email_backend.FastEmailBackend')
class XYZTest(TestCase):
    ...