Ability to initiate an email message from within an ongoing Discussion. Ideally a colleague can start a discussion, and after we figure things out we can send an email to whatever was the subject, and keep the history of what was discussed.
When I @mention someone in an email, I would like the user's contact to be automatically added as a recipient or at least given the option to tag them in the body to make specific call outs.
Current owner of a meeting should be able to transfer ownership of an event to another user of their choosing so that the new user can manage the event going forward.