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Method to Indicate Best Sources of Information for Microsoft 365 Copilot
Message center notification MC1310687 (14 May 2026) is all about the introduction of authoritative sites for SharePoint Online in Microsoft 365 Copilot. An authoritative site marks the content in the site as trusted and prioritizes its use in Microsoft 365 Copilot chat responses and search results. In other words, marking sites as authoritative gives Copilot a clear instruction that the content found in those sites should be used whenever possible.
The change is rolling out now and should be complete for targeted release tenants by the end of May 2026. General availability follows in mid to late June 2026.
A Good Idea
It’s an idea that seems stunningly obvious when you think about it. Different versions of files can find their way into different sites. People can copy files or save files sent around as attachments into their OneDrive for Business accounts or other sites. Or people download files to create local copies and then upload the files to a different site. For whatever weird and wonderful reasons, different versions of files can end up being scattered around a tenant.
Until now, Microsoft 365 Copilot has had no way to distinguish the copy of a file found in one site over a file found elsewhere. Restricted content discovery (RCD) can block Copilot from using material found in specific sites. The material might be obsolete or simply too sensitive to be processed by AI. Used intelligently, RCD is a great way to set guardrails for Copilot’s consumption of information within a tenant by setting blocks for content retrieval.
Authoritative sites give positive direction to Copilot chat and search by saying that the content found in marked sites should absolutely be used in responses to user prompts. As such, it has the opposite effect to RCD.
Setting up Authoritative Sites
Like many other changes in SharePoint Online, the initial introduction of authoritative sites is through PowerShell manipulation of site settings. I’d expect an update for the SharePoint Online admin center to follow in due course. For now, you must set the isAuthoritative flag for a site by running the Set-SPOSite cmdlet:
Set-SPOSite -Identity "https://office365itpros.sharepoint.com/sites/BlogsAndProjects" -IsAuthoritative $true
Make sure that you use the latest version of the SharePoint Online management PowerShell module. I used version 16.0.27215.12000.
Once the flag is set for a site, it takes a few hours for Microsoft 365 Search to register the change and give site contents priority for search results. When everything is ready, you’ll notice that search lists results found in the authoritative sites at the top, and that the results are marked with a checkbox and “From your organization” to indicate their trusted status.
Given the human inclination to accept items at the top of lists, authoritative sites seems like a good way to guide Microsoft 365 Copilot users (the premium license is required) to use the best information.
No Guarantee
Much as I like the concept of authoritative sites, they are no silver bullet and won’t fix a mess of digital debris, poorly planned permissions, or site sprawl. Authoritative sites are a step forward along the path to managing SharePoint information in an intelligent manner that’s ready for AI interactions. Don’t expect miracles but do make authoritative sites part of the deployment plan for Microsoft 365 Copilot.
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