Open forums and private teams are great, but, I think, an addition of open (and private) boradcasts. In boradcasts, only the creator of the list (and the members he/she invites him/her self) only can post or message and others can only read. Basically, read only forums (or teams) for almost all and read/write for some would be great. It'll enable us to create an announcement broadcast list, for example. We might be wanting to post important announcements and not let it get spamed by other messages.
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