Preparing for Microsoft 365 Copilot: what data can Copilot see?
5 min read · Updated on 20 October 2026
Microsoft 365 Copilot searches your email, chats and files to give answers. Copilot does not get any extra permissions to do this. The problem is usually permissions that are already too broad.
Copilot follows existing permissions
According to Microsoft, Copilot only surfaces organisational data that a user has at least view permission for. Copilot uses the same access controls as the rest of Microsoft 365.
Is a file encrypted with a sensitivity label from Microsoft Purview Information Protection? Then Copilot respects the usage rights of that user.
Microsoft also states that prompts, responses and data from Microsoft Graph are not used to train the underlying language models.
Where is the risk?
Copilot makes visible what was already accessible. A salary list on a site shared with the whole organisation could always be opened. Nobody was looking for it. With Copilot, a simple question can surface such a file.
Common causes are:
- Sites or files shared with the Everyone except external users group.
- Organisation-wide sharing links or Anyone links that were never cleaned up.
- Folders with different permissions, which breaks permission inheritance.
- Sites without an active owner that nobody manages any more.
Getting insight
SharePoint Advanced Management is included with a Microsoft 365 Copilot licence. It gives your IT administrator data access governance reports in the SharePoint admin centre. These reports show, among other things, sites with many sharing links and sites where content is shared with all internal users.
With a site access review, your IT administrator asks the site owner to check access. The owner removes unnecessary users, groups and sharing links.
Microsoft Purview Data Security Posture Management (DSPM) offers risk assessments. These show which sites contain sensitive data and are overshared.
Shield temporarily, protect permanently
Restricted Content Discovery removes a sensitive SharePoint site from organisation-wide search results and from Copilot. Permissions do not change. People with access can still open the files. Microsoft describes this as a temporary measure while you clean up permissions. It only works for SharePoint sites, not for OneDrive. Use it sparingly. Microsoft warns that shielding too many sites makes Copilot answers less complete.
For the long term, Microsoft recommends:
- Sensitivity labels on sites and files, optionally applied automatically.
- Microsoft Purview Data Loss Prevention (DLP) for Copilot. This excludes files and emails with a specific label from processing by Copilot.
- A DLP policy that makes Copilot decline when a prompt contains sensitive information.
- Restricting organisation-wide sharing links and Anyone links at tenant level.
Checklist before you start
- Run the data access governance reports and review the sites with the most sharing links.
- Have site owners check their access through site access reviews.
- Temporarily shield the most sensitive sites with Restricted Content Discovery.
- Decide which sensitivity labels you use and apply them.
- Set up DLP for Copilot for your most sensitive data.
- Start with a small pilot group and see what Copilot finds.