Thinking about #USENET/ !GNUsocial analogies (thanks, @smj) made me think of this: when replying to a notice that was posted to a group, if you think your reply will be of interest to the other members of the group, be sure to mention the group in your reply. The USENET analogy is this: mentioning the group is like posting a "Follow-up", and replying without mentioning is more like posting a "Reply" via email.