Canvas gives you two tools to contact students – Announcements & Inbox Messages. In both cases, your course MUST BE PUBLISHED.
Sending announcements is easy. Click on the Announcements menu, click +announcement, give title & body, and click SAVE at the bottom. This action will send email notifications to your students. If you need to receive a confirmation email, please go to your notification settings under your personal settings menu. The announcement notification will be sent to the members of your course.
You can also send “Conversations.” Canvas calls their messaging method “Conversations” and you use the tool called Inbox. You can control receivers by using this tool. You can choose the entire course, by sections, by groups, by individuals, etc. Please review the Canvas article on these tools for detailed explanations.