When you sign into Exchange Online, OWA now loads with a new message in the Preview Pane. It is introducing a new setting and has set a new default. The Reading Pane will not display a message on first loading OWA.
This may be considered a privacy setting, so message content isn't displayed on first load. For years we open Outlook on our desktop and it opens the first message in our Inbox inside the reading pane.
Do you have any thoughts as to how this might be used?