Microsoft announces big Outlook update for Android and iOS
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Delegate in Android
Most of these new features are related to Calendar, so here is a couple that seems to be among more important than others. First off, Outlook for Android and iOS will soon get sync shared calendars, which means users will be able to view and edit shared Office 365 or Outlook.com calendars.
If you absolutely can't wait to make use of the new feature, there's a workaround that allows you to start using it immediately. The only thing you'll need to do is re-accept the sharing invitation from Outlook on iOS or Android.

Meetup in Android
The iOS app receives a new feature that allows users to add a message when responding to a meeting invite. This new feature will be pushed to Outlook for Android on a later date.
The update is slowly making its way to Android and iOS devices, so give it some time if you don't see any of the new features right away.
source: Microsoft
Things that are NOT allowed: