Well, we can see some inconsistencies among the packages listed above.
Surely, ns7 has a new concept/use case that ns6 does not have: the remote account provider. In this case the user-deleted and group-deleted events can't be catched.
After some months of real world experience, I'd prefer ns7 behaves exactly like ns6 on the local account provider scenario. Thus when a user/group is deleted, also local data dirs are removed.
But on remote scenario nothing can be done.
Confirmed. Mail aliases must be created manually. For local accounts provider on a mail server, an UI enhancement during user/group creation could be adding a checkbox that enables mail alias and shared mailbox creation.