One nice pattern in that [override settings][1] page might be useful here.  If you use the decorator it will ensure cleanup to settings when you make modifications.  More robust, ie. when an exception happened somewhere before you had a chance to clean up.

  [1]: https://docs.djangoproject.com/en/1.4/topics/testing/#overriding-settings

```
from django.test.utils import override_settings

@override_settings()
def test_email_flag_true(self):
    settings.MITX_FEATURES['ENABLE_INSTRUCTOR_EMAIL'] = True
    ## do your tests
    ## don't have to clean up, decorator will take care of it
```

That seems pretty clean to me