Preserve Microsoft Teams Private Chats: What Actually Works
If you need to stop users from permanently deleting Teams private chat messages—for legal or regulatory reasons—the right control is Litigation Hold on the user’s mailbox in Microsoft 365.
Private chats (1:1 and small group) are stored in hidden folders in each participant’s Exchange Online mailbox. Placing that mailbox on Litigation Hold preserves the content even if the user deletes it in Teams.
What counts as “private chat”
- Included: 1:1 chats and group chats from the Chat tab.
- Not included: Channel posts (standard/private/shared). Those map to group or special mailboxes and need their own coverage.
Why Litigation Hold (user mailbox) is the right answer
- Captures the compliance copy of Teams private chats.
- Blocks permanent deletion until you remove the hold.
- Legal-defensible preservation; discoverable via Purview eDiscovery.
Why the other ideas fall short
- DLP policies: Prevent leaks; they don’t preserve deleted content.
- Litigation Hold on group mailboxes: Protects channel posts, not private chats.
- Teams Retention policies: Great for lifecycle (retain/delete on a schedule) but not a substitute for an indefinite, legal hold.
How to enable Litigation Hold (GUI)
- Go to Exchange admin center → Recipients → Mailboxes.
- Open the user → Mail tab → Litigation hold.
- Turn On. Set Duration (or leave Unlimited).
- Save.
PowerShell (bulk-friendly)
# Connect-ExchangeOnline first
Set-Mailbox user@contoso.com -LitigationHoldEnabled $true -LitigationHoldDuration Unlimited
# Verify
Get-Mailbox user@contoso.com | FL LitigationHoldEnabled,LitigationHoldDuration
Tip: Use a CSV and a loop to enable holds for many users.
Pair with retention for full coverage
- Use Microsoft Purview retention policies to manage Teams channel messages and to apply time-based retention for chats if required.
- For private/shared channels, apply policies/holds to their dedicated mailboxes too.
Verify preservation
- Delete a test chat message.
- In Purview eDiscovery, search the user’s mailbox for that time window—the message should appear.
- Confirm
LitigationHoldEnabled : Truevia PowerShell.
Governance notes
- Limit who can place/remove holds (Compliance Admin roles).
- Track hold reasons, start dates, and scope.
- Monitor mailbox growth; enable archives and adjust quotas if needed.
Bottom line
To preserve Teams private chats and prevent permanent deletion, activate Litigation Hold on each user’s Exchange Online mailbox. Use retention policies alongside it to cover Teams channel posts and to meet your data lifecycle requirements.
