Nice work pulling the notification logic out of the Edition mixin :thumbsup:. The class/module nesting has got a bit hairy here though: `Edition::GovUkDelivery::Notifier:: GovUkDelivery`... How about pulling the `Notifier` class out to lib and renaming it `EditionNotifier`? Now the logic has been teased apart, it doesn't feel like it belongs here in the `Edition::GovUkDelivery` mixin.