Thanks, Simon. I want everyone to be able to see the topics in the category if they go looking for it, so I don’t want to use category permissions. I also don’t want them to mute the categories because that function is a little too robust for what I’m going for. I’m experimenting with Hide categories according to user group membership, though.
Perhaps the solution would be to make members of the group ‘Watch first post’ in the category. They’ll now get notified every time a post is made, right, and so they don’t need to see these posts in their summary emails? Not AS ideal, but acceptable, I think. Maybe in the future there will be a way to ‘Include topics in summaries’ option?