Reply All by Meeting is missing in the New version
Within the old version of Outlook 365 you could open an email and click on the menu on the right side of the email and select from the dropdown the Reply All by Meeting. Great feature. For when you need to schedule a meeting about the email that has been sent. Now I have to go back to the old version to do this.
The old Outlook Online included a reply option that allowed the user to set up a meeting invite from an e-mail by having an option of replying with a meeting invite. This was an incredibly useful tool and it should be in the new Outlook online.