Registering unregistered users on first email a la mailman?

After a lot of searching I suddenly bumped into this discussion:

which mentions “staged users” (nonmembers) and most other things I was looking for.

Would this be the correct match for my process? There seems to be some confusion in the referenced discussion on how to configure this beast. Is this a supported feature? Is there more documentation relating to it?

(FWIW it would be very helpful with something resembling a normal documentation ToC that links to relevant articles for each feature group so one could find and read appropriate documentation “linearly” without the guesswork of trying out different search terms on the support forum)