Teams Meeting Chat missing with external participants

Question

Teams Meeting Chat missing with external participants

Mcintosh, Rebecca 201

I had a meeting with some internal and some external meeting participants that we used the chat for during the meeting. The chat has since been completely cleared and we are seeing these banners:

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Can you clarify why we are seeing these messages and why the meeting chat was cleared against our tenants policies? Our chat policies should not clear the chat and we do not have restrictions in place with externals from our tenant. We hosted the meeting from our tenant.

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Answer accepted by question author

Jess-Q 12,415 Microsoft External Staff Moderator

Hi @Mcintosh, Rebecca

In a Teams meeting chat, a copy of every message is saved for each person in the meeting both your team and the external guests. Each of those copies follows the retention rules of that person's own organization. If more than one organization's rules apply to the same chat, the strictest "delete" rule takes priority, and the messages are removed for everyone no matter who set up the meeting, and even if some participants have no delete rule at all.

So even though you hosted the meeting and your own settings are meant to keep the messages, if one of the external organizations has a shorter "delete" rule for Teams chats, that rule will clear the shared meeting chat for all participants.

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For more details, please refer to: Microsoft Teams messages about retention policies

Manage retention policies for Microsoft Teams

Because the banner doesn't specify which organization's policy triggered it, it may help to review the following three areas in order:

Check your company policy

In Microsoft Purview > Solutions > Data Lifecycle Management > Policies > Retention policies, review every policy that includes Teams chats not just your main one.

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Look closely for:
- A separate, shorter delete policy scoped to specific users or groups,
- An adaptive scope whose conditions the affected users now match (license/group/department changes can pull users in automatically).
- A narrower delete policy overriding your main "retain" policy

Check the external participants' organizations.

Because the chat is shared, check if any external org with a shorter delete policy can remove the messages for everyone.
Important note: while you can fully review the retention policies within your own tenant, you generally won't have visibility into the external organizations' retention configurations. As a result, ruling out an external delete policy usually requires confirming directly with those external parties, rather than something that can be checked from your side alone.

Contact Microsoft support

If that's truly confirmed, and there is no delete policy exists anywhere, neither within your own tenant nor in any of the external participants' organizations this may indicate a possible service-side issue, which would be best raised with Microsoft Support for further investigation.

A technical support engineer can perform a remote session to investigate the situation, verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.

Here’s what your Microsoft 365 Global Admin (IT Admin) should do next:

Submit a Service Request: The Global Admin should create a service request with Microsoft support to get advanced technical assistance and diagnostics. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin.   
Find Your Microsoft 365 Admin: If you’re unsure who the Global Admin is within your organization, you can find guidance on locating them here: How do I find my Microsoft 365 admin? - Microsoft Support.
If your subscription is managed through a Microsoft partner or reseller, they can also assist with opening a support request and liaising with Microsoft on your behalf.

Note: If you’re an end-user, please coordinate with your Office 365 Global Administrator to handle these steps. 

Hopefully this clears things up and clarify why the banner appears and what to check next.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Mcintosh, Rebecca 201 Reputation points

2026-06-17T08:56:58.7733333+00:00
Thank you for the detailed explanation!

Can you confirm a couple more things for me please?

Can I retrieve copies of the deleted messages via eDiscovery? I can view the audit log showing me that messages were sent ("Posted a new message") but I can also see newer entries relating to Exchange and mailboxes and deletion of messages

To mitigate this in the future - do external policies impact meetings held from our tenant within a Team/Channel meeting?

How does sensitivity labelling impact this? If we mark something critical on our side, can these still be overwritten by an external users policy?
Jess-Q 12,415 Reputation points Microsoft External Staff Moderator

2026-06-17T15:23:06.79+00:00
Hi @Mcintosh, Rebecca

Thank you for your follow-up questions.

Based on your questions, I’ve looked into this further and found the following information that may help clarify the situation:

Can the deleted messages be retrieved through eDiscovery?

Yes, but only if the messages were still being preserved when they were deleted even after a message disappears from the Teams app. Aside from what appears in the Teams app, Teams also keeps a separate hidden copy of each message for compliance purposes

For more details, please refer to: Where Teams content is stored

Whether you can actually get them back depends if a "retain" policy or a legal/eDiscovery hold was switched on at the time, if yes the hidden copy was protected, and you can try searching for it in eDiscovery. If nothing was protecting it and the deletion already finished and the copy is gone.

For more details, please refer to: How Teams retention policies support retain and delete actions

One point to note: the audit log can confirm that messages were sent and deleted, but it does not show the actual message content, so for the content itself, eDiscovery is the right tool.

Here is a reference: Find and delete Microsoft Teams chat messages in eDiscovery | Microsoft Learn

Do external policies affect meetings held inside a Team/Channel?

A channel meeting is different from a normal meeting chat.

In a normal meeting chat, external participants’ retention policies can affect the shared chat, and messages can be deleted for all members of the conversation.

For a channel meeting, the conversation appears in the channel’s Posts/Conversations feed instead of behaving like a normal meeting chat. Channel messages are handled as Teams channel content and are managed through Teams retention policies for channel messages.

For more details, please refer to: Channel meetings in Microsoft Teams

For more details, please refer to: Where Teams content is stored

One thing to keep in mind: channel meeting conversations are visible in the channel, so the channel membership should match who should be able to see the discussion.

Does a sensitivity label stop the chat from being deleted?

No. A sensitivity label does not stop retention deletion as sensitivity label is mainly about protection and meeting controls. It can control things like who can bypass the lobby, who can present, who can record, encryption, watermarks, and preventing copying or forwarding of chat but those are all about access and protection, not deletion.

So, even if a meeting or chat is marked as Critical or Confidential, that label does not override a retention policy. It may help protect access to the content, but it does not decide how long the chat is kept.

For more details, please refer to: Use sensitivity labels to protect calendar items, Teams meetings, and chat

I hope this helps clarify the differences and gives you a clearer idea of what to check next.
Jess-Q 12,415 Reputation points Microsoft External Staff Moderator

2026-06-18T15:33:49.48+00:00

Hi @Mcintosh, Rebecca,

I hope you're doing well. I wanted to follow up and check if you've had a chance to review the replies provided regarding the issue we discussed. Any updates or insights you could share would be greatly appreciated.
Mcintosh, Rebecca 201 Reputation points

2026-06-22T09:07:32.0933333+00:00

Thank you for your replies - I think this answers all my queries
Jess-Q 12,415 Reputation points Microsoft External Staff Moderator

2026-06-22T09:11:43.9933333+00:00

Hi @Mcintosh, Rebecca,

I'm glad my explanation was helpful to you, if you ever run into any issues or have questions while using Microsoft 365 or Office, feel free to post them here in our Q&A forum. I'm always happy to help. If my response helped guide you toward the next step, feel free to click "Accept Answer" so the post can be highlighted and pinned to the top, making it easier for others in the community who are facing similar issues to find the information quickly.

1 additional answer

Your answer

Mcintosh, Rebecca 201 Reputation points

2026-06-17T08:56:58.7733333+00:00

Thank you for the detailed explanation!

Can you confirm a couple more things for me please?

Can I retrieve copies of the deleted messages via eDiscovery? I can view the audit log showing me that messages were sent ("Posted a new message") but I can also see newer entries relating to Exchange and mailboxes and deletion of messages

To mitigate this in the future - do external policies impact meetings held from our tenant within a Team/Channel meeting?

How does sensitivity labelling impact this? If we mark something critical on our side, can these still be overwritten by an external users policy?
Jess-Q 12,415 Reputation points Microsoft External Staff Moderator

2026-06-18T15:33:49.48+00:00

Hi @Mcintosh, Rebecca,

I hope you're doing well. I wanted to follow up and check if you've had a chance to review the replies provided regarding the issue we discussed. Any updates or insights you could share would be greatly appreciated.
Mcintosh, Rebecca 201 Reputation points

2026-06-22T09:07:32.0933333+00:00

Thank you for your replies - I think this answers all my queries
Jess-Q 12,415 Reputation points Microsoft External Staff Moderator

2026-06-22T09:11:43.9933333+00:00

Hi @Mcintosh, Rebecca,

I'm glad my explanation was helpful to you, if you ever run into any issues or have questions while using Microsoft 365 or Office, feel free to post them here in our Q&A forum. I'm always happy to help. If my response helped guide you toward the next step, feel free to click "Accept Answer" so the post can be highlighted and pinned to the top, making it easier for others in the community who are facing similar issues to find the information quickly.

Answer 1

The banners indicate that external participants were in the meeting chat and that one of the organizations involved applied a retention policy that removed older messages. In external chats, the shortest applicable retention policy wins, and that policy can come from any participating organization, not only the tenant that hosted the meeting.

Because of this, even if the hosting tenant’s policies do not delete chat messages, stricter message‑retention settings from an external participant’s organization can still cause messages in the shared meeting chat to be deleted, which is why the chat history appears cleared and why the informational banners are shown.

To avoid this behavior, meeting organizers who require long‑term chat retention should limit attendance to people in the same org or move sensitive/long‑lived discussions to an internal‑only chat or channel where only the hosting org’s retention policies apply.

References: