Currently, I can either send a message immediately - as it is - from the Canvas Inbox or cancel the message. I cannot prepare a message and then Preview it first. Many teachers don't realize that URL are actually displayed as hyperlinks and also also - the editor right now isn't a wysiwyg editor - the message may look quite different with e.g. attachments and media embeds.
Allows users to preview the message so they can decide if everything is OK and send the message as is, edit it, or discard it.
admin,instructor,student,ta
