You can send a Canvas (not email) message to individual students on your class roster. It may even be a more reliable way to reach your students than email.
If you need to send a message to the entire class, see Sending a Canvas Message to Your Class.
Keep in mind that this sends a Canvas message, not an email message. So your student will have to log into Canvas to see your message. Most IAIA students log into Canvas multiple times each week; some daily.
Messaging an Individual Student
What the Student Sees
You can place a star by messages you want to list for future reference. Then you can list only starred messages.
Starred messages can only be viewed for your Inbox. (Not for sent messages.)
The Canvas messaging system may even be a more reliable way to reach your students than email.