Organisations should include the collaboration locations most likely to hold sensitive content and the adjacent repositories where those files and messages are stored. In practice, that means prioritising Teams chats and channels, then extending discovery to attachments, Calendar, Contacts, Exchange Online, OneDrive Business, and SharePoint Online. The right scope is the one that matches how employees actually share and retain information.
How to choose the right Microsoft 365 discovery scope
The practical rule is to start with where sensitive information is most likely to be created, discussed, stored, or forwarded in normal business flow. In Microsoft 365, that usually means scanning collaboration spaces first, then the adjacent storage and messaging systems that preserve the same content in different forms. If the scope does not reflect actual usage, discovery becomes noisy and misses the places that matter.
Teams is often the highest-value starting point because it combines chat, channels, and file collaboration in one workflow. That is why organisations should treat Teams as a primary discovery surface rather than a narrow messaging app. The same logic extends to the repositories that back those conversations and attachments, especially when staff use them to exchange drafts, approvals, customer data, or operational detail.
Discovery scope should be defined by content movement, not by product boundaries. Files shared in Teams often live in the Ultimate Guide to NHIs, but the important point for Microsoft 365 scanning is that the content path crosses multiple stores, including OneDrive Business and SharePoint Online. When people forward information from chat into email or calendar workflows, Exchange Online and Calendar can become part of the same discovery universe.
That broader view matters because sensitive material is frequently stored outside the original source system. The NHI and Secrets Risk Report notes that nearly half of exposed secrets reside outside code repositories, in collaboration tools and messaging platforms, which is a useful reminder that discovery should include the places employees actually use to exchange information, not just the archive where security teams expect it to be.
For organisations trying to prioritise scope, a sensible order is: Teams chats and channels, then attachments and linked files, then Exchange Online, OneDrive Business, SharePoint Online, Calendar, and Contacts where those stores hold business data that has been shared, scheduled, or circulated. That sequence catches the highest-probability locations first while still covering the repositories that commonly retain the same content after it leaves the original conversation.
Where discovery scope usually breaks down
The most common mistake is scanning only one repository and assuming it represents the whole Microsoft 365 estate. That approach misses the way content is duplicated across chat, mail, file storage, and scheduling tools. Another failure mode is over-scoping every location equally, which creates excessive review noise and makes it harder to distinguish truly sensitive content from routine collaboration.
Another issue is forgetting that Microsoft 365 locations support different retention and sharing patterns. A file in OneDrive Business may be linked from Teams, copied into SharePoint Online, and then referenced in email. If discovery rules only target the source location, the same item can remain undiscovered in the downstream repository where access is broader or retention is longer.
This is why scope decisions should be tied to business workflows. The goal is not to enumerate every Microsoft 365 workload because it exists. The goal is to include the repositories that materially change the likelihood of finding sensitive content, the likelihood of duplication, and the likelihood that content remains searchable after the original conversation has ended.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST CSF 2.0, CIS Controls v8 and NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | ID.AM — Asset Management | Discovery scope is an inventory decision across M365 content stores. |
| Recommendation — Map the Microsoft 365 locations that hold sensitive content and keep the inventory aligned to actual workflows. | ||
| CIS Controls v8 | 3 — Data Protection | Discovery scans support identifying where sensitive data resides and is exposed. |
| Recommendation — Include the Microsoft 365 repositories most likely to contain sensitive data in your data discovery program. | ||
| NIST AI RMF | MAP — Map | If automated discovery or AI-assisted classification is used, the data flow map must capture every relevant M365 location. |
| Recommendation — Document where content moves across Microsoft 365 before relying on automated discovery outputs. | ||
Practitioner Guidance
What to prioritise: Begin with Teams, then extend coverage to the repositories that preserve its attachments and conversation content. If a location is heavily used for customer data, internal approvals, or regulated material, it belongs in the first-wave discovery set even if it is not the original creation point.
What to verify: Check whether the chosen locations match actual sharing behaviour, not just the Microsoft 365 service catalog. If users routinely move documents from Teams to OneDrive Business or SharePoint Online, or use Exchange Online to circulate sensitive material, those paths should be visible in discovery results.
Common mistake: Treating discovery as a one-time mailbox scan or a file-share exercise. Microsoft 365 sensitivity is often distributed across chat, mail, files, calendar data, and contacts, so a narrow scope can give false confidence.
Practitioner takeaway: The best discovery scope is the one that follows content as employees actually collaborate, because that is where sensitive material is most likely to appear, persist, and be missed.
Framework Alignment
OWASP Non-Human Identity Top 10: Apply discovery and visibility thinking to collaboration and storage locations where secrets and sensitive material often spread beyond their original system.
NIST Cybersecurity Framework 2.0: Use the Identify function to inventory where sensitive content lives across Microsoft 365 and align scanning scope with real business workflows.
NIST Privacy Framework: Map discovery coverage to data locations and processing paths so classification and minimisation decisions reflect how information is actually stored and shared.
NIST AI Risk Management Framework: If discovery is extended into AI-assisted collaboration or automated content handling, use governance and mapping practices that preserve traceability over where information flows.
Related resources from NHI Mgmt Group
- How should organisations govern sensitive data moving outside Microsoft 365?
- How do organisations decide whether to prioritise data discovery, access governance, or runtime monitoring first?
- How do organisations decide whether to prioritise AI discovery, data governance, or broader compliance mapping first?
- How should organisations govern identity risk when using AI assistants like Microsoft 365 Copilot with enterprise data?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 19, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
