Hi,
Unfortunately, that feature is not available at the moment and you will have to download/copy the email from your outlook to a folder of your local PC. Then you have to drag and drop it to the desired webex teams chat space.
However, you can submit a new feature request via https://ciscocollabcustomer.ideas.aha.io/.
Submitted ideas will be evaluated by our product teams for upcoming releases and will be responded to so you know where things stand.