A student in my class requested the following feature, which makes a lot of sense to me: they want to receive email notifications for posts from the instructor/TAs only.
Our feed is pretty high traffic, so getting emails for all posts is overwhelming. However, they want to be sure they don't miss anything from the instructional staff.
As the instructor, I could check the "send an email" box for every post I make, but I prefer to reserve that for urgent messages and let the students use their notification settings otherwise.