Students and Instructors receive daily notifications on the Activity Stream. Students receive information of due dates, what they have missed, announcements, new discussions, new content loaded, etc. Instructors receive information on new gradable items, performance alerts, past due items, etc. You can manage what information you will receive in the activity stream, your emails and on the mobile app.
This document shows you where to see which email address is used for clickUP notifications and email.