Microsoft announced a few weeks ago changes regarding the storage location for tasks in Planner. Starting in January of next year, a copy of some tasks will always be stored in the user’s Exchange mailbox. The Planner service will remain the primary storage location for all tasks. If a task is assigned to multiple users, each user will receive a copy of that task in their respective mailbox.

Reasons for this move are to add tasks to eDiscovery in the future and to further the merging between To-Do’s and Planner. For the user, nothing will change for existing To-Do’s, Planner tasks as well as Outlook tasks.

Notice:
This only affects tasks that are assigned. Unassigned tasks will remain in the Planner service.

The announced rollout timeline is as follows:

Global Tenants: From mid-January – end of February 2021
GCC Tenants: End of February – beginning of April 2021