Digital
Thank you Digital for your detailed explanation. I think we talked at cross purposes, it was my bad as I used the word 'reply' in an misunderstanding way.
I meant with 'reply' an answer to the complete discussion (orange Button) not when I mention someone explicitly with his ID (which is almost the same as using the 'reply under the post' button).
When I'm following a discussion, which I do here, I only get a message on the very next entry (see my post achlys) or if I get mentioned ('replied to'). But there seems no way to get every entry made (and not only the very next entry or when replied to me explicitly).
Again, thank you for your patience.