Outlook is your email. Microsoft 365 Copilot Coaching is a helper that suggests edits while you write.
How-to · INT · INT.2
Microsoft 365 Copilot Coaching in Outlook — use one, leave one
Possibility first: you can open Coaching on a O365 email draft you already own, use one suggestion, leave one unused, confirm it is yours now when you send. Apply-all is the fail. It is helping, not doing your work in this use case
Worked example
You drafted a note to yourself. Coaching offers a full rewrite plus a few line edits.