Hi @FRANCESCLOSE
If your school has "New Analytics" enanbled, you can go to the "New Analytics" screen, select "Course Grade", and click the "Message" icon to send a message to all students who have a course grade within a particular range. There is a page with screenshots describing the process at https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-send-a-message-to-an-individual-student...
Be aware that this would be sending a message to the students through the Canvas Inbox, which is not the same as their campus email.
