How do I reply to a message in Conversations as an instructor?
Canvas makes it easy to reply to messages from other users in your Conversations Inbox.
If you want to reply to a submission comment, you can reply using submission comments in your Inbox or directly from your assignment or quiz.
In Global Navigation, click the Inbox link.
Click the Conversation you want to respond to . Hover over the timestamp and click the Reply icon  within the message or the Reply icon in the toolbar .
Note: If there is more than one recipient, you can reply-all to the conversation and everyone included will see your reply.
Reply to Message
Type your reply in the message field . You can attach a file or media . When you are ready, click the Send button .
View Sent Message
Your message appears in the preview text of the conversation  and at the top of the individual thread .