The Inbox is extremely cluttered and unusable. A functionality to have the messages categorized by Course and also the functionality to have our own folders of messages will help.
If you'd like to request new functionality that allows users to create their own custom folders, would you please edit the idea to focus it on that request?
The submission comments in inbox are extremely valuable for seeing assignment feedback from students, but for a large class it also can become extremely cluttered, would it be possible to at least filter by unread?