Hi Frank and welcome to the Canvas Community! You can't actually email a class in Canvas because Canvas doesn't have a true email function. You can use Conversations (the Inbox) in Canvas but there are some important differences between Conversations and email systems like Google or Outlook. Here are a couple of documents that describe how Conversations work and how to use this to message your entire class.
How do I use the Inbox as an instructor?
How do I send a message to all course users in the Inbox as an instructor?
Hopefully, using the Inbox to message the entire class will work in your situation. One of the differences between email and Conversations worth noting is that you cannot send an message to students while the course is unpublished. At our institution, notifications in Canvas are set up so that messages sent in the Inbox are sent to the student's institutional email account as well, but this may not be the case in your situation.
I hope this helps and best wishes!
Yes is a help
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