Microsoft Teams chat archiving

Why Teams chats matter for retention and discovery

Decisions, approvals, customer complaints and HR conversations increasingly happen in Teams rather than email. If a chat contains a record you need to keep, or personal data someone asks for, it is in scope in the same way as an email. That raises the same questions:

• How long should chats be kept, and when should they be deleted? Our email retention policy guide applies to chat too.
• Can you find every relevant message, including edited and deleted ones, for a dispute or investigation? See email eDiscovery.
• Can you search chats when answering a subject access request? See searching for subject access requests.
• What happens to a leaver's chats when their account is deleted?

Teams also behaves differently from email in ways that matter: messages can be edited or deleted after sending, and Microsoft warns that what users see in the Teams app is not an accurate reflection of what is retained or deleted for compliance.

How Microsoft 365 retains Teams chats

Microsoft's native route is Microsoft Purview retention policies for Teams. From Microsoft's documentation:

• Separate locations: retention policies use the Teams chats and Teams channel messages locations. Teams messages are not covered by retention policies set for Exchange mailboxes, and Teams policies do not affect email.
• Where the data sits: copies of chat messages are stored in a hidden folder in the mailbox of each user in the chat; channel messages use a similar hidden folder in the group mailbox. These folders are for compliance search, not for users or admins to browse.
• Edits and deletions: under a retention policy, the original of an edited message is copied, and a deleted message is moved, to a hidden SubstrateHolds folder, where eDiscovery can still find it for the retention period.
• What is not retained: code snippets, voice memos recorded in the Teams mobile app, thumbnails, announcement images and reactions.
• Files and emails used in Teams have their own retention policies through SharePoint, OneDrive and Microsoft 365 group locations.
• Private channels: Microsoft moved private channel messages into group mailboxes from late 2025, so they now follow the Teams channel messages location and inherit the parent team's settings.
• Leavers: if a user under a Teams retention policy is deleted, their mailbox becomes an inactive mailbox so the chats stay discoverable.

Deletion is not instant: Microsoft's timer job typically takes one to seven days to process expired items, and Microsoft's own example shows a delete-after-one-day policy taking up to 16 days to remove a message completely. Our Cloud Security site covers Microsoft Purview more widely.

Searching Teams chats with Purview eDiscovery

Because retained Teams messages live in Exchange mailboxes, Microsoft Purview eDiscovery can search them alongside email, including messages users have edited or deleted while they are still retained. Holds placed by eDiscovery, Litigation Hold or another retention policy suspend permanent deletion.

Microsoft retired the classic Content Search and eDiscovery (Standard and Premium) experiences on 31 August 2025, so searches now run in the current Purview eDiscovery experience. Which eDiscovery features you have depends on your Microsoft plan. For holds specifically, see our guide to legal hold.

If your organisation already runs Purview retention well, native Teams retention may cover you. Microsoft itself recommends Microsoft 365 retention for its range across workloads, including Teams. Where NinjaOne helps is in keeping a copy outside the tenant, in the same place as your archived email.

How NinjaOne handles Microsoft Teams

NinjaOne treats Teams channels and private chats differently. From NinjaOne's documentation:

NinjaOne describes private chat backup as available with the Backup + Archiver subscription. Its documentation is not consistent about whether private chat carries a separate charge, so we confirm that when we quote. The bundles are compared on NinjaOne SaaS Backup Standard vs Archiver bundles.

Setting up private chat archiving in NinjaOne

Private chat backup is not switched on automatically. NinjaOne's documented process is:

1. In the End-User Portal, open the Private Chat tab and go to Credential Settings.
2. Reauthenticate the backup admin account for the Microsoft 365 tenant.
3. Enter the application ID and application secret and use Test & Save Connection; the status should show as active. If you back up several tenants, credentials are set for each one.
4. Activate the accounts whose private chats you want to keep, either all at once or individually. Backup does not start until accounts are activated.

Once chats are backed up, authorised users can download them for a chosen date range as EML, PDF or CSV, with text only or with attachments. Downloads arrive as ZIP files of up to 1 GB each, and if you do not choose a date range you get the last 90 days. That makes it practical to hand a set of chats to HR, legal or a requester. We can help with the app registration and activation as part of setting up NinjaOne Archiver.

Native, NinjaOne, or both?

For most organisations the answer is a mix:

• Use Purview retention policies for Teams chats and channel messages if you have the licences and want retention and deletion managed in place.
• Use NinjaOne Archiver where you want a copy of private chats outside the tenant, held with your archived email and backups, and downloadable in standard formats.
• Decide retention periods for chat deliberately. Many organisations keep chat for less time than formal email records; UK GDPR's storage limitation principle applies either way. See email retention and UK GDPR.
• Tell staff what is kept. Your acceptable use and privacy notices should say that Teams chats are retained and may be searched.

For the wider Microsoft picture, see Office 365 email archiving.

How Forever Systems helps

We supply NinjaOne SaaS Backup with Archiver and can help you decide how Teams fits your retention policy, set up the private chat credentials and activation, and show reviewers how to find and download chats. We can also look at your current Teams retention policies in Purview so the two approaches do not contradict each other.

Whether private chat archiving adds to the price is confirmed when we quote, along with the bundle, seats and term. Contact us to plan Teams chat archiving alongside your email archive, or go back to Office 365 email archiving.