Adding a revised patch with the following changes.
1. Added a new automated ...

Adding a revised patch with the following changes.

1. Added a new automated PHP unit test for testing the configuration form.
2. Changes to the config variable naming to ensure consistency throughout the module with the name of the config variable in the schema file.

Regarding testing of mail sending and email blocking - As per the usual rule of writing tests we should test dependencies and sending of mails is a dependency. We might have to think of mocking sending of emails. Also, the key functionality is done via hook and as hooks are related to the API and not part of custom code they need not be tested. What do you think of this?