The "Send Availablity" feature is iOS is one of the most useful features I've ever used. I actually switch away from a desktop interface to the mobile version of Outlook just to use that feature. It is that great! It would be AWESOME if the Outlook for Mac team could bring that feature to the Mac Desktop client.
Patrick Gudat commented
Imagine sending a meeting request, not invite but an intent for a time, to team people in email and processing the reponses. Or soliciting free times next week and getting the response back on what works/doesn't. This all ties into the use case around availability.
Can we add the feature that's available already in Outlook for iOS to add your current availability in the email reply.