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Private channels have long empowered focused collaboration among a subset of a team’s members. Whether you’re managing sensitive projects, driving confidential initiatives, or simply need a space for more targeted discussions, private channels offer the control and privacy your team needs.

Now, private channels are evolving to meet the needs of modern teams. In response to customer feedback, we are introducing enhanced flexibility, greater scalability, and streamlined compliance management. Read on to learn about these key enhancements and how to prepare.

Why Private Channels Matter

Private channels offer a dedicated space for conversations that benefit from added structure, persistence, and control. They’re especially valuable when navigating sensitive topics like budgets, HR discussions, managing project-specific workstreams, or collaborating with clients and vendors who require limited access .While chat are ideal for quick exchanges, private channels help keep discussions organized, make shared files easier to find, and help ensure conversations remain accessible over time, all while giving you more control over who can access.

What’s Changing—and Why It Matters

To support growing usage and help simplify compliance, private channels will now use a group mailbox (like shared channels) instead of storing messages in individual user mailboxes. This change unlocks several key benefits:

🚀 Expanded Limits

Helping to Simplify Compliance

By aligning private channels with group-based storage, compliance policies (e.g., retention, legal hold, DLP, eDiscovery) can be applied at the team (Microsoft 365 group) level, helping to reduce complexity and driving consistency across channel types. For example, one retention policy can be applied to the team’s group, instead of managing a separate policy for private channels.

Organizations with compliance policies (retention, legal hold, DLP, eDiscovery) for private channels must ensure those policies are also applied to the team’s group scope before migration begins. Existing policies for user mailboxes will continue to apply; post-migration, new private channel data will be governed by policies of the group mailbox.

What Compliance Admins Need to Do

To enable a smooth transition and help maintain compliance coverage, follow the below:

1. Microsoft Purview Hold and eDiscovery

Before Migration:

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  • In Microsoft Purview compliance portal, update hold policies to include the team’s Microsoft 365 group mailbox in addition to user mailboxes.
  
  
  
  

After Migration:

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  • New data will reside in the group mailbox.
  
  
  • For full eDiscovery, search both user and group mailboxes.
  
  
  
  

Note: Private channel message history (edits/deletes) in user mailboxes under an existing hold will remain in their preserved user library folder until the hold expires.

2. Microsoft Purview Data Loss Prevention (DLP) Policies

Before Migration:

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  • In Microsoft Purview compliance portal, update DLP policies to include team’s group.
  
  
  
  

After Migration:

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  • Check that the DLP policies are scoped to the group mailbox for private channels.
  
  
  
  

3. Microsoft Purview Retention Policies

Before Migration:

• In Microsoft Purview compliance portal, go to solutions à Data Lifecycle Management à Retention policies


• Create Teams channel messages policy scoped to Teams having equivalent Retention type and duration similar to existing private channel retention policies.

After Migration:

• Set retention policies for the parent team with all channels in the team in mind, including private channels.

What’s Next

This update helps make private channels more scalable, manageable, and compliant. It’s a big step forward for organizations that rely on Teams for secure, structured collaboration.

Migration is scheduled to begin in late September 2025 and is expected to be completed by the end of December 2025 for the worldwide cloud. During this period, private channel data will gradually move from user mailboxes to the team’s group mailbox. Private channels can be used throughout the migration. Special cloud migration will happen in early 2026.

Migration can start or end at different times for each tenant during the rollout period. To track progress, a new PowerShell command will be available for tenants to check whether their migration has started or is completed. This post will be updated soon with details on the PowerShell command.

We’ll be updating public documentation soon and will share links here.