Urgent: Historical Chat Messages Missing in Microsoft Teams Despite Retention Policies Not Enabled

Hello @Shivani Soni,

Thank you for reaching out to the Microsoft Q&A forum.

I understand that several historical chat conversations are no longer visible for multiple users. Since no retention policies are configured, we need to determine whether the messages are truly deleted or simply not visible in the Teams interface.

Please follow the steps below carefully. Each step helps us identify where the data is stored and whether it still exists in the backend.

Step 1/ Confirm the Type of Conversation

Please confirm whether the missing messages were:

• 1:1 chats
• Group chats
• Or channel conversations inside a Team

This is important because chat types are stored in different locations. In Microsoft Teams, 1:1 and group chats are stored in Exchange Online mailboxes, while channel messages are stored in SharePoint. The troubleshooting path depends on this distinction. For reference on where Microsoft Teams data is stored, please see: Location of data in Microsoft Teams

Step 2/ Check Outlook on the Web

For one affected user, please:

• Sign in to Outlook on the web.
• Navigate to the folder: Conversation History
• Open the subfolder: Team Chat

For your information, 1:1 and group chat messages from Microsoft Teams are stored in the user’s Exchange Online mailbox under this hidden folder. If the messages are still present there, the data has not been deleted. This would indicate a Teams client or indexing visibility issue rather than data loss.

Step 3/ Verify Mailbox and License Status

Please confirm the following for affected users:

The user still has an active Microsoft 365 license assigned.

The Exchange Online mailbox is active and not converted, disabled, or recently migrated. If a mailbox was removed, converted, or temporarily unlicensed, Teams chat visibility can be affected even though the data previously existed.

Step 4/ Perform a Content Search in Microsoft Purview

As an administrator, please:

• Go to the Microsoft Purview compliance portal.
• Navigate to "Solutions" > "eDiscovery" > "Content search" targeting:
  • The affected users’ mailboxes
  • Relevant participants
  • The approximate date range of the missing chats

If the messages appear in Content Search results, this confirms the data still exists in the backend and is retrievable. If no results are returned, we need to investigate whether the content was permanently deleted. Detailed guidance on running a Content Search can be found here: Get started with Content search

Note: To run this Content search, you must have these role

• eDiscovery Manager
• eDiscovery Administrator
• Compliance Administrator

Step 5/ Review Audit Logs

Within Microsoft Purview, please check the Audit log for:

• Teams message deletions
• Mailbox item deletions
• Purge actions

If the messages were deleted through an administrative or compliance action, there should be a corresponding audit record.

If the messages cannot be found in Outlook, Content Search, or Audit logs, and no retention policies are configured, this may require escalation to Microsoft Support for backend investigation.

Please share the results of each step so we can determine the appropriate next action.

The disappearance of historical chat messages in Microsoft Teams, especially when retention policies are not configured, can be concerning. Here are a few potential reasons for this issue:

1. Retention Policies: Although you mentioned that retention policies are not enabled, it's important to ensure that there are no conflicting policies from other organizations if the chats involve users from different organizations. Sometimes, messages can be deleted based on policies set by other organizations involved in the conversation.
2. Technical Issues: There may be technical issues or bugs affecting the visibility of chat messages. It's advisable to check for any known issues with Microsoft Teams that might be causing this behavior.
3. User Actions: If any of the participants in the chat deleted the messages, they would no longer be visible to anyone in the conversation. However, if this affects all users, it seems less likely to be the cause.
4. Compliance Holds: If any of the users' accounts are under compliance holds or litigation holds, it might affect the visibility of messages, although they should still be discoverable through eDiscovery.
5. App Updates or Changes: Changes or updates to the Teams app could also lead to temporary issues with message visibility.

If the issue persists, it may be beneficial to contact Microsoft support for further investigation into the missing chat history.

References:

• How retention works with Microsoft Teams
• Messages in the Teams and Viva Engage apps are unexpectedly deleted by retention policies