Shared mailbox users will no longer be able to add or edit tasks, upload attachments, or add comments in Microsoft Planner due to permission model limitations. A temporary workaround is available but will be phased out in 30 days. Convert shared mailboxes to user mailboxes for uninterrupted functionality. Instructions are provided.
Applies to: Planner
Source: mc.merill.net — data via Merill Fernando's open archive (MIT).