You can use the Gradebook to send messages to your students. Message subjects are filtered based on specific assignment categories:
Haven't submitted yet—students who haven't submitted the assignment. This category does not include students who have been manually awarded a grade, even if they did not submit the assignment. Once a grade has been awarded for an assignment (either automatically or manually), Canvas no longer verifies actual submissions.
Haven't been graded—students whose assignments have not yet been graded (submitted or unsubmitted).
Scored less than [point value]—students who earned a grade on their assignment less than X number of points.
Scored more than [point value]—students who earned a grade on their assignment more than X number of points.