An email that needs action becomes a task: Add to tasks in its menu. Or write a task of its own with New task under Tasks.
A task has what to do, a due date and a note. Tasks made from an email open that email; tasks made from an outreach campaign open the prospect.
Tasks groups them as Overdue, Today, Tomorrow, Later and No due date. Tick one to mark it done, and Remove done tasks clears them away. Today's tasks also show on Today.
Tasks are personal: each person sees their own.