For starters, there is a new tab bar at the bottom is more modular and customizable. The “More” button has been added to the tab bar, which will allow you to access Contacts and Files in its first iteration, followed by Apps at a later date. Basically, any installed Teams apps that also support Outlook will start to appear in the Apps section, but a dedicated mobile store is in the works too. Rollout will begin with Android, followed by iOS.
Additionally, Search is being renamed to “Feed” based on the multipurpose role it plays. Apart from discovering content such as files and emails, it will also surface a scrolling feed of To-Do items, news, and more. File and Contacts will be migrated to the tab bar instead of being directly in Search.
Finally, the Fast Action Button (FAB) in the inbox view currently allows an action of “New email”, but it will soon have a caret button (“^”) that will allow you to perform other actions such as creating a new event too.
Although Microsoft hasn’t defined concrete timelines for the respective rollouts of these features, it has mentioned that most of them will come first to Android, rather than iOS. Based on the announcement and the screenshots, it doesn’t seem like Outlook customers on these platforms will have to wait too long.