Added additional note that tests use locmem email backend.
@@ -549,6 +549,9 @@ To specify this backend, put the following in your settings::
This backend is not intended for use in production -- it is provided as a
convenience that can be used during development and testing.
+Django's test runner :ref:`automatically uses this backend for testing
+<topics-testing-email>`.
+
.. _topic-email-dummy-backend:
Dummy backend
