High-Level Summary:
- You may need to add Private Teams Channel Group Mailboxes to existing holds
- You may need to change Enterprise Teams Retention Settings
Microsoft is rolling out a change to Microsoft Teams Private Channels, beginning in October 2025 (see Microsoft roadmap ID: 500380). The planned changes will expand the capabilities of Private Channels but will also require companies that use Private Channels to take steps before the change is implemented to maintain retention and preservation efforts.
What are Teams Private Channels? Teams Private Channels are channels within any Teams site that have more restricted access than the general Teams site. For example, a Teams site for the HR department that has a separate, Private Channel with restricted access for compensation-related discussions and information. By default, any Team owner or member can create a Private Channel.
What is changing? Currently, Teams Private Channel messages (also known as “conversations”) are stored in the individual Exchange mailboxes for each member of the Private Channel. Once the change is implemented, Private Channel messages will be stored in the group mailbox associated with the Team. According to the Microsoft Tech Community, beginning in October 2025, Microsoft will migrate existing Private Channel messages from user mailboxes to the group mailbox. Private Channel message history (edits and deletions) stored in user mailboxes will not be migrated.
The change also impacts Microsoft’s Data Lifecycle Management features. Microsoft currently allows organizations to configure separate retention policies for Teams Private Channel messages. Once the enhancement is rolled out, organizations will no longer be able to configure a separate retention policy for Private Channel messages.
What does this mean for preservation? Due to these upcoming changes, organizations using Private Channels should act now to update existing legal holds that include the preservation of Private Channel messages. To preserve Private Channel messages, a Teams group mailbox must also be added to hold.
Additionally, organizations must understand that the retention policy configured for Teams Channel messages will also apply to Private Channel messages. Prior to the rollout of the enhancement, organizations should consider the appropriate retention period for all Teams Channel messages and revise their Teams Channel message retention policy, if necessary.
For additional information or assistance with legal holds or evaluating your current Teams retention, please contact Gunster's eDiscovery team.
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This publication is for general information only. It is not legal advice, and legal counsel should be contacted before any action is taken that might be influenced by this publication.
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