Open Teams channel/chat for email recipients
Add option to "Discuss in Teams" which opens a group chat with all email participants.
OmniSynThesis - Joscelin commented
Chat invoking Teams is ok for me, but then please open the installed, active, signed-in app, if available, instead of Teams web app.
Lobosco, Joseph C commented
Or just make chats from teams populate to Outlook.
Some people think by using Teams the messages also route to Outlook. It doesn't. Huge oversight in how people work with both.