Send email to non registered user in a group

Looking at Description of various user states in Discourse (Admin / Moderator / Staff / Developer / Other) this should be the common behavior in Discourse. Anyway the user should get something from Discourse like a message to the link to the thread or an alert that the forum can customize otherwise the feature is not so useful. It is like a contact form without chance to write to the user that started.

  1. We checked in that, when the staged user is validated to get emails from discourse to get something with the same settings (also changing them). Seems that as staged user doesn’t get anything from discourse at all and there are no errors or anything in the logs.

  2. I cannot find anything about the group box on Google for Discourse (why there isn’t a documentation outside the forum and the few pages on GitHub? But this is a more personal rant). We want that users of the forum can join in that category, and I am not sure if this fit our needs, or it is easy to use compared toa category.