Ediscovery for Teams Chat: The Complete Guide

How to Manage Ediscovery for Microsoft Teams Chat

Since its launch in 2017, Microsoft Teams Chat has become one of the biggest sources of discoverable data inside organizations. With Teams users receiving 153 chat messages a day, interrupting their work every two minutes, conversations accumulate fast — across one-to-one chats, group threads, channels, and meetings. And when an investigation lands, legal teams often discover that pulling these conversations together is far more complicated than it looks inside the app.

In this article, you’ll learn how to manage ediscovery for Teams Chat, including how Teams Chat actually stores data, why chat evidence is uniquely challenging to collect and review, and the best practices that can help legal teams stay prepared long before an issue arises.

Want a comprehensive roadmap to master modern corporate ediscovery? Get the guide.

Understanding Microsoft Teams Chat for ediscovery

Microsoft Teams Chat has become the default tool for employees to ask questions, make decisions, share files, and hash out project details. But what feels like one continuous conversation inside the app is actually a collection of messages, files, and meeting-related content stored across several Microsoft 365 services. 

For legal teams, understanding how Teams Chat works behind the scenes is the first step toward collecting the right data and avoiding surprises during an investigation or dispute.

Teams Chat types

Teams supports several types of conversations, each storing messages and files in different ways. Understanding these distinctions is essential for identifying where relevant chat data lives and how each conversation type affects preservation, collection, and review.

One-to-one chats – Teams chats between two users, often used for quick questions, decisions, or file sharing. These chats can move fluidly between text, calls, and screen shares. Since the history persists across devices, they are a common source of discoverable business communication.

Group chats – Multi-person chats created outside channels, frequently used for cross-functional projects or fast-moving collaboration. They support shared files, reactions, and message edits, and their membership can change over time — an important factor when identifying custodians and scoping legal holds.

Channel conversations – Chats that occur within a specific Teams channel tied to a team or department. These messages follow threaded structure, making context easier to follow, but they’re stored in the team’s group mailbox rather than individual user mailboxes.

Meeting chats – Conversations tied to a scheduled Teams meeting, where participants exchange notes, links, and decisions before, during, and after the meeting. Depending on settings, meeting chats may persist for all participants or only certain attendees. They may also link to recordings, transcripts, and other meeting artifacts.

Teams Chat features 

Teams includes several features that shape how conversations unfold and how evidence appears during review. These capabilities influence what gets stored, where it lives, and how complete a chat record may be when reconstructed for an investigation or discovery request.

Message search and save functions – Teams allows users to search across chats, channels, and meetings using keywords, names, or file references. Users can also save individual messages for quick access later, which often helps pinpoint key communications during early fact-finding.

Message editing and deleting – Users can edit messages to correct or refine wording, or delete them entirely. While chat history in the app may appear updated, underlying versions may still be retained or removed depending on administrative retention and governance settings.

Conversational threading – Channel messages support threaded replies that keep discussions organized around specific topics. This structure helps reviewers follow context more easily, especially when multiple related conversations occur simultaneously within the same channel.

@mentions and notifications – By tagging individuals or groups, users can highlight important messages and draw specific people into a discussion. These notifications often signal action items, approvals, or decisions that become relevant during review.

File attachments and link sharing – Files shared in chats are stored in the sender’s OneDrive, while channel files live in SharePoint. The chat simply references these locations. As a result, reviewing file context requires an understanding of where each document actually resides.

Reactions and interactive elements – Emojis, likes, polls, and other interactive tools let users express agreement, acknowledgment, or sentiment without typing a new message. These subtle cues can matter during investigations by clarifying intent or team dynamics.

Teams Chat data storage 

Teams Chat looks unified in the app, but behind the scenes it’s distributed across several Microsoft 365 services. 

• One-to-one and group chat messages are stored in hidden folders within each participant’s Exchange Online mailbox. 
• Channel conversations are stored in the group mailbox associated with that team.
• Private or shared channels create additional, distinct mailboxes with their own membership and access rules.

Files aren’t stored with messages at all: chat attachments live in the sender’s OneDrive, while channel documents are stored in that team’s SharePoint site. Meeting chats, recordings, transcripts, and notes may reside in yet another set of locations depending on organizational policies.

During ediscovery, Teams chat data from these locations is collected and reassembled so reviewers can see messages, shared files, timestamps, participants, edits, deletes, and other relevant metadata in context. Understanding this architecture helps legal teams identify which mailboxes and repositories need to be included in holds, collections, and review.

Teams Chat ediscovery challenges

As you might guess, pulling usable evidence out of Teams Chat isn’t straightforward. The platform’s structure, storage patterns, and user behavior often create unexpected hurdles for legal teams trying to preserve, collect, and reconstruct accurate records for review.

Runaway data volume that grows by the hour

A single custodian may generate thousands of messages per week across one-to-one chats, group threads, channels, and meeting conversations. Messages also stack with reactions, edited messages, shared links, GIFs, and auto-generated Teams notifications. Multiply this by dozens of custodians on a project, and the dataset grows exponentially.

From an ediscovery perspective, sheer message velocity becomes a risk: key facts may be buried under a flood of informal chatter, and files shared via chat can fork into multiple versions with unclear provenance. 

Legal teams must account not just for message content but for how communication patterns create massive volumes of reviewable material.

Our Custodian Collection Tracker can help you create a clear collection plan. 

Reconstructing complete conversations across fragmented storage

For ediscovery, Team’s scattered architecture creates a practical challenge: reconstructing a single conversation often requires pulling data from multiple locations, sometimes across custodians. 

For example, a message saying, “See the updated spreadsheet,” may point to a file stored in one user’s OneDrive, while a threaded reply exists in a channel mailbox the custodian doesn’t own. 

Without a clear understanding of how these elements fit together, collections can easily miss critical context or, worse, entire conversation segments.

Challenges with preserving and reconstructing Teams Chat history

In ediscovery, one of the hardest parts of handling Teams Chat history is that messages aren’t static. They can be edited or deleted long after they’re sent, and whether earlier versions remain accessible depends on retention settings, legal holds, and organizational policies.

One-to-one chats — Teams chats between two users — are often central in workplace disputes, and they can be especially tricky when participants edit or remove messages. These changes create gaps between what users see in the app and what’s actually stored. Meeting chats, ephemeral conversations, disappearing links, and guest-user activity add additional complications.

For legal teams handling ediscovery for Teams Chat, the challenge is determining what the “true” conversation looked like at the time decisions were made. Small changes in chat history can shift context, intent, or meaning, making early preservation and careful handling essential.

Legal hold gaps caused by Teams’ complex membership model

Placing a legal hold on Teams Chat isn’t as simple as selecting a custodian. A hold on an individual user protects their one-to-one and group chats, but channel conversations require holding the underlying team mailbox. Private and shared channels each have separate mailboxes and membership structures that also need to be included.

If legal teams don’t map membership carefully — who belonged to which channel, when, and with what permissions — they risk preserving only part of a conversation or overlooking entire message sets. This is one of the most common Teams-specific pitfalls in litigation: a legal hold that appears complete in theory but is incomplete in practice.

Guest users, external collaborators, and unclear governance trails

Teams makes it easy to collaborate with vendors, partners, contractors, and clients through guest access. But those same conveniences introduce ediscovery challenges: guest accounts often have inconsistent permissions, may leave the organization abruptly, or may use unmanaged devices.

Messages involving guests are still discoverable, but the underlying data might live in places corporate legal teams don’t anticipate, especially if the guest shared files from their own cloud system or if access was revoked. 

Tracking who said what, when, and with which permissions is as much a governance problem as a technical one. For organizations operating in regulated industries or high-stakes matters, guest access can create significant gaps in auditability, data lineage, and defensibility during review.

Teams Chat ediscovery best practices

Managing Teams Chat in ediscovery requires intentional preparation. Clear governance, thoughtful configuration, and well-scoped preservation practices give legal teams a strong foundation before an issue ever arises. These best practices outline what organizations should consider to stay ready for Chat-heavy matters.

Get the guide: Ediscovery 101

Configure retention and governance settings before you need them

Many Teams ediscovery failures stem from retention settings that were never configured — or never revisited. Teams, SharePoint, OneDrive, and Exchange each have their own retention rules, and Teams-specific content (like meeting chats and private channels) behaves differently.

Establishing clear retention periods that align with regulatory requirements and risk tolerance ensures that content is neither deleted too early nor retained longer than necessary. Organizations should also review who can create teams, private channels, or external collaborations.

Proactively setting and enforcing governance policies means your legal team won’t be scrambling to reconstruct missing conversations, identify ownership of shared files, or untangle meeting chat history when a claim or investigation lands on your desk.

Apply legal holds through a coordinated, well-documented process

Legal holds in Teams work best when legal, IT, and HR follow a shared process for identifying who was involved, confirming when they participated, and communicating obligations clearly. Instead of relying on a static list of custodians, build a repeatable workflow that captures how work actually moves through Teams — including who joins or leaves a channel, when files are shared, and when related meetings occur.

Documenting each step of your hold process helps show what was considered, who was included, and how decisions were made. This operational consistency is often more important than technical detail: it reduces confusion, shortens response times, and ensures Teams-related evidence is handled the same way across matters.

Save time, reduce costs, and improve outcomes with legal hold software for the modern enterprise.

Identify custodians, channel membership, and file ownership with precision

Understanding who participated in which Teams conversations is essential for building a clear factual record. Unlike email, Teams activity often spans one-to-one chats, group threads, multiple channels, recurring meetings, and files stored across different OneDrive or SharePoint locations. A single “conversation” may involve several people moving between these spaces over days or weeks.

Mapping these relationships early gives legal teams clarity about who contributed to which discussions, where shared files originated, and how decisions moved across Teams. This helps avoid blind spots during review, reduces unnecessary collection, and ensures the investigative story reflects how people actually collaborated. 

Accurate custodian and channel mapping is one of the highest-value steps for establishing what happened — and who was involved.

Collect all relevant artifacts – not just visible messages

Teams Chat content includes far more than text. Relevant evidence may include:

• File attachments and version history
• Reactions that signal approval or acknowledgment
• Edited message versions
• Deleted messages preserved through retention
• Meeting chats, transcripts, and recordings
• Card elements, polls, or link previews
• System messages (added users, removed users, calls, recordings started/stopped)

Effective collection ensures each of these components is preserved with its metadata intact: timestamps, user IDs, thread IDs, and storage paths.

Legal teams should verify that export workflows reliably capture both message content and the surrounding context. Missing artifacts can distort meaning or create ambiguity in review, especially when files or decisions were shared exclusively through Chat.

Additional reading: How to Plan and Execute Defensible Collections

Use search and filtering tools to surface the right Teams Chat data

A successful internal or forensics investigation requires mastery of ediscovery search for Teams Chat. Messages may live in different mailboxes, files appear as links rather than attachments, and meeting chats often behave like separate conversations. 

Teams need search and filtering tools that can pull together messages across one-to-one chats, group threads, channels, and meeting history. Filters for participants, timestamps, keywords, reactions, and file references help narrow results and surface the most relevant portions of a conversation. 

Because context matters, it’s important to search not just for exact matches but for surrounding messages that show how the discussion developed. A thoughtful search strategy can dramatically reduce noise and make downstream review more focused and efficient.

Learn more about DISCO’s intuitive ediscovery search function that thinks like you do.

Review conversations in context to avoid misinterpreting the record

Individual chat messages rarely tell the whole story. Teams threads can jump between topics, incorporate files that live elsewhere, or reflect decisions made in meetings that generate their own separate chats, transcripts, and recordings.

Reviewers need tools capable of reconstructing full conversation flows—including edits, deletes, reactions, and timestamps—so meaning isn’t lost in isolated excerpts. Threading and transcript reconstruction significantly speed review by grouping messages by both chronology and context.

This contextual approach is particularly important for sensitive matters like HR investigations, regulatory inquiries, or cross-functional disputes where intent, timing, and reaction patterns matter as much as the words themselves.

Here’s how DISCO ingests Microsoft Teams data to locate and group conversations.

Address privacy and regulatory obligations specific to chat ecosystems

Teams data often contains personally identifiable information, health or financial data, employee performance discussions, customer information, and cross-border communication. Because retention and access vary across regions and tenants, organizations must carefully align Teams practices with regulations like GDPR, CCPA, FINRA, and industry-specific requirements.

Best practices include:

• Minimizing unnecessary access during review
• Restricting privileged or highly sensitive channels
• Documenting compliance controls for defensibility
• Validating that exports preserve required metadata without over-collecting private content

Compliance becomes complex when guest users, external tenants, or regional data boundaries are involved. This is why privacy-by-design practices must be built into Teams governance and ediscovery workflows.

Learn how to navigate legal hold compliance challenges.

Train employees on how discoverable chat actually is

Many employees treat Teams chats like hallway conversations — informal, disposable, and private. They’re often surprised to learn that:

• Chat edits and deletes may still be preserved
• Meeting chats persist even after participants leave
• Reactions and emojis can reflect intent
• Files shared in chat are fully discoverable
• Channel membership changes don’t erase historical content

Educating users on Teams’ discoverability reduces risky behavior and helps ensure more consistent, responsible communication. Even a short awareness briefing can dramatically improve outcomes during investigations or litigation.

Conclusion

Teams Chat is one of the most comprehensive communication and collaboration tools on the market, but its underlying architecture makes it far more complex than it appears. Understanding its moving parts — from how chat types map to storage locations to how edits, deletes, and membership changes affect the record — gives legal teams a clearer picture of what needs to be included in a hold or collection. 

By planning ahead with thoughtful governance and well-scoped preservation practices, organizations can approach chat-heavy matters with greater confidence and fewer last-minute surprises.

Take the next step in managing Teams Chat ediscovery

Teams Chat matters can get complex quickly. Having tools that help you make sense of that data can make the work faster and more manageable. DISCO Ediscovery leverages state-of-the-art AI and integrates seamlessly with your existing litigation or investigation processes. 

DISCO also offers technology and services that support legal teams as they collect, organize, and review Teams Chat data — whether it’s for an internal inquiry or a larger dispute. When Teams evidence becomes high-volume or fast-moving, DISCO’s support can help teams stay organized and keep work moving forward.

Here are ways DISCO can support your next Teams-heavy matter:

• Learn more about DISCO Ediscovery.
• Explore Cecilia, our suite of AI-powered tools.
• Learn more about DISCO’s managed services and forensics support.‍
• Request a demo.