Planner Uses Exchange Online for Microsoft 365 eDiscovery and Compliance

Planner assigned to me tasks

Tasks and Exchange Online

Office 365 Notification MC229058 (8 December 2020) had the headline “Planner tasks storage location update.” In fact, it meant nothing of the sort. Planner continues to use Azure to store its plans and tasks while taking the same route as Teams and Yammer by storing copies of tasks (compliance records) in Exchange Online mailboxes to make those items available for eDiscovery. Microsoft’s original intention was to push the change out in early 2021. Things didn’t quite turn out as they thought, but Planner data is now in Exchange Online mailboxes. In my case, it seemed like a background process populated data for preexisting tasks on 14 December 2021. This closes a gap in Microsoft 365 compliance which existed since Microsoft launched Planner in 2016.

The copies of Planner tasks stored in Exchange Online are automatically indexed and become available to compliance functionality like eDiscovery (core and advanced), communication compliance policies, and retention policies. Microsoft hasn’t said yet when Planner data will be picked up by other compliance features but this can be expected over time.

Substrate and Digital Twins

The Microsoft 365 substrate and brings items together from across Microsoft 365 to let common services like Microsoft Search and eDiscovery work efficiently. Obviously, it’s much easier when a service like Search doesn’t need to process multiple repositories. To make this possible, Planner uses the substrate to create “digital twins” when tasks are created and edited and stores them as items in the mailboxes belonging to the assignees. These items are also called compliance records or secondary copies. The Planner data in Azure remains the storage repository of record.

Tasks assigned to a single user result in the creation of a compliance record in their mailbox. Tasks assigned to multiple users generate compliance records in the mailboxes of all assignees. This mimics the approach taken by Teams when it creates compliance records for personal chats and conversations in private channels.

And like Teams and Yammer, digital twins of tasks assigned to hybrid and guest accounts are stored in cloud-only mailboxes (aka shards), which are also indexed. Unassigned tasks are ignored.

Teams stores its compliance records to a hidden folder in the non-IPM part of mailboxes, the part which isn’t usually exposed by clients like Outlook and OWA. Yammer stores its compliance records in a similar place. Planner uses a folder called AllToDoTasks to store its compliance records. This folder also holds compliance records for To Do items. To generate just the items for Planner tasks, Exchange Online has a MAPI search folder called Folder Memberships\Assigned to Me. Planner displays the contents of this folder when users take the Assigned to Me option in the Planner hub. Exchange Online also stores personal tasks created with Outlook or To Do in the Tasks folder in the client-visible part of the mailbox.

End users aren’t affected by storing compliance records for Planner in Exchange Online. The Planner browser and mobile clients continue to use the Graph API to access plans and tasks in Azure.

Integration with To Do

The original text of MC229058 says that the update supports work “to build deeper integrations between To Do and Planner. Perhaps the existence of copies of Planner tasks in the same mailboxes will make the type of integration demonstrated in the Teams Tasks app easier. There’s no obvious sign of what these integrations might be, but time will tell.


Learn more about Planner, the Microsoft 365 substrate, and eDiscovery in the Office 365 for IT Pros eBook. Updated monthly to keep abreast with important changes in apps like Planner.

2 Replies to “Planner Uses Exchange Online for Microsoft 365 eDiscovery and Compliance”

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.