Outlook Mobile now supports delegate access to Exchange Online mailboxes. By granting fuil access to a delegate, they can open and work with a mailbox, and send messages using the SendAS or SendOnBehalfOf permissions. The new feature underscores the advantage Outlook mobile enjoys over other mobile Office 365 email clients.
You can configure Send As and Send on Behalf of permissions to allow Exchange Online users to send messages for an Office 365 Group. All is well if the messages arrive, but if they don’t, the NDRs might not get to where you think they should go, such as a folder in the Recoverable Items structure. That’s OK if the sender was told that a problem exists with a message, but they don’t know anything happened.