Currently, there seem to be these "list_type" users: list_owner
(implied), list (subscriber), authorized_senders, and testers (???), (not
including the white/black/confirm/invite pseudo-types) It appears I'll be adding "moderators" (actually a holdover from a previous version) and
"digest"

At least right now, these are all called, "sublists" - except the list
owner, which really doesn't fit in within the model

http://dadamailproject com/support/documentation-dada-3_0_3/MailingList_Subscribers pm html#subscription_list_model

What are/would be the "roles" of these types in relation to a
discussion list and moderation?

Well, right now, it's all much more simpler than you're laying out At
least for Dada Bridge, there's basically two modes,

Announce-only

Discussion

• Announce Only only the list owne can send to the list

• Discussion Only the list owner and subscribers can send to the list

And, that's it

There's a few different options:

The, "Authorized Senders" feature was added, since there's situations
where you want a bunch of people to be able to send to an announce- only list, but not necessarily other subscribers I'm not sure if the,
"Authorized Senders" really is useful outside of an announce only list

etc, etc,

I haven't really thought about hard and fast roles for all of this, so
here are my opinions of what you've laid out:

• list_owner => ALWAYS sends without restriction, NEVER moderated,
  ALWAYS moderates???

Sure, but the, "Always moderates" should only be there, since
something may happen where the moderators shouldn't moderate - like
when they get into a situation where they shouldn't moderate their own
message I think people would find it useful for the list owner to not
have to moderate, though

• list => receives approved messages, OPTIONALLY sends messages,
  OPTIONALLY moderated, OPTIONALLY allowed to moderate (in lieu of using
  "moderators", as in a "random pool of subscribers")

That's all fine - you may want to think of the, "announce-only" and,
"discussion" modes as pretty high level, though

• authorized_senders => OPTIONALLY sends without restriction,
  OPTIONALLY moderated (or are they like the list_owner)???,

A good question It could def be a pref, either way

For things like these:

NEVER receives (unless also a subscriber), NEVER allowed to moderate (unless also a moderator)

and,

>

• moderators => NEVER sends (unless also an authorized_senders), NEVER receives (unless also a subscriber), OPTIONALLY allowed to moderate
  (in lieu of only using list_owner)

and,

• "non-subscriber" => OPTIONALLY sends messages (if
  open_discussion_list), ALWAYS moderated (if moderation is used), NEVER receives, moderates,
  etc

I never really thought about in such detail I don't mind such a
model, but we'd just as well better rewrite the plugin ;)

1. Should the list_owner ALWAYS receive a moderation accept/reject
   message? Or should they be exempted if using moderators and/or a random pool of subscribers?

I think there should at least be an option to be exempted But you'll
run into problems, as I've noted above

>

1. Should authorized_senders ALWAYS be treated as a list_owner with unrestricted sending, or should there be an OPTION to moderate those
   posts? More like a white list for unmoderated sending?

Again, I think keeping it as an option to have their messages
moderated would be nice, but I also think authorized senders make more
sense in announce-only mode

1. Therefore, by definition "moderators" (only) moderate, and "authorized_senders" (only) send? If both roles are wanted for a
   user, the e-mail name must assigned both list_types?

Basically I think