Microsoft 365 Copilot can draft the email, summarize long meetings, do spreadsheet magic, and much more. But before you roll it out across your organization, you should stop and ask if your Microsoft 365 environment is ready for it. Getting that groundwork right is what decides whether Copilot works for your organization or against it.
Note: Deciding whether Copilot is the right AI platform in the first place is a separate question, and we compare the main options in Copilot vs. Claude vs. Gemini.
What “Ready for Copilot” Actually Means
As explained by Microsoft, Copilot can only return data the requesting user already has permission to access, and it honors the security controls you already have in place, such as multi-factor authentication, Conditional Access, and sensitivity labels. In general, there are two kinds of consequences that stem from this.
First, what Copilot can’t see, it can’t use:
- If a user doesn’t have access to a file, Copilot can’t access it on their behalf. The obvious things like editing a document, summarizing a spreadsheet, or pulling numbers from a sales report are blocked the same way the user would be.
- The above also applies to the quieter case where Copilot is just trying to gather context for an answer by reading relevant files. Permissions that are too tight, or scoped to the wrong people, can leave Copilot’s responses shallower or less accurate than they should be. To make things worse, Copilot doesn’t usually signal when it’s missing relevant context (because it doesn’t know that it’s missing it). If a file the user can’t see would have improved an answer, Copilot just gives the thinner version, and the user has no way to tell the difference.
Second, what Copilot can see, it will use:
- Anything your team has access to is on the table. That includes documents nobody has updated in years, superseded versions of files that should have been archived, or PDFs sitting next to their replacements with no clear signal as to which is current. As a result, Copilot might quote from an outdated version with the same confidence as the current one and give answers that look authoritative but contain stale prices, retired procedures, or other outdated information.
- Permissions in many Microsoft 365 environments are looser than they should be. Copilot’s job is to dig efficiently, and that greatly increases the likelihood of an employee stumbling upon something they technically have access to but shouldn’t, such as a salary spreadsheet, a draft layoff plan, or legal correspondence on a deal they were never read into.
- Additionally, the more material Copilot has to read and weigh before producing an answer, the longer it takes to do so, and the more tokens it consumes along the way.
We should also point out that if your organization shares files or sites with external partners, vendors, or clients, and those organizations have Copilot enabled, their employees’ Copilot can surface your shared content too. A SharePoint site shared with a consulting firm, a OneDrive folder linked to outside counsel, or guest access granted to a contractor’s email address all mean that someone else’s AI assistant can now read, summarize, and reason over your data, governed by whatever sharing permissions you set (or forgot to revisit) months or years ago.
What all of this adds up to is that Copilot readiness comes down to who has access to what, what content is still worth keeping around, and whether the controls that protect all of it are doing their job. None of those questions is exotic on its own, and most of them are good security hygiene with or without AI in the picture. They just become a lot more visible once Copilot starts answering your team’s questions every day.
Getting Each Part of Microsoft 365 in Order
Microsoft 365 is several interconnected systems, such as SharePoint, OneDrive, Teams, and Outlook, which store and share data in ways that are not always obvious, even to people who use them every day. A file shared in a Teams chat, for example, does not live in Teams. A meeting recording does not live in the meeting. Understanding where data actually lives, and who can reach it, is the foundation of getting your environment ready for Copilot.
SharePoint
SharePoint is where most of your organization’s shared documents live, and it is also where most of the oversharing risk tends to accumulate. The problem is that the defaults lean toward openness.
External sharing is on by default for SharePoint organizations, set to the most permissive level (“Anyone”). Unless an admin tightens this, files can be shared through “Anyone” links: unauthenticated, transferable, and impossible to track once they leave your walls.
Then there is the “Everyone except external users” group (often abbreviated EEEU), which Microsoft’s own Copilot team marks as one of the most common oversharing patterns. When a site or folder is shared with EEEU, every internal user in the organization has access. Before Copilot, a file shared this way might sit unnoticed for years. Now, a single prompt can pull it into a summary, a draft, or a response that the employee takes at face value.
The good news is that the fixes here are straightforward and worth doing whether or not Copilot is on your roadmap:
- Set the default sharing link type to “Specific people” or “Only people in your organization” at both the organization and site level, and confirm it isn’t left on “Anyone.”
- Set expiration dates on any remaining Anyone links and restrict them to view-only.
- Run Microsoft’s Data Access Governance reports to find sites shared with EEEU, sites with active Anyone links, and sites with the broadest permission footprints.
- Review sharing settings individually for anything that stores sensitive content (HR documents, financials, legal files, client work) and tighten them to “Specific people” or “People with existing access.”
Most of the tips above are standard data protection best practices. Copilot just makes the cost of not implementing them a lot more visible.
OneDrive
OneDrive is the personal side of Microsoft 365 storage. Every user gets their own OneDrive for Business account, and its sharing settings are tied to SharePoint’s, so OneDrive sharing can match the organization-level SharePoint setting or be more restrictive, but never more permissive.
The part that catches most organizations off guard is how much content ends up in OneDrive without anyone actively choosing to put it there. Files shared in private Teams chats are stored in the sender’s OneDrive, not in Teams. Ad hoc and scheduled meeting recordings save to the organizer’s OneDrive, and 1:1 call recordings go to the recorder’s. Transcripts follow the same pattern. Over months and years, this adds up to a large volume of shared, searchable content that most users have long forgotten about, and Copilot can reach all of it, which is why you should do the following:
- Review file sharing links that are still active on old OneDrive content, especially anything shared externally.
- Check whether meeting recordings have a retention policy or are just piling up indefinitely.
- And if your organization records meetings by default, make sure that decision was intentional and that the people whose conversations are being recorded and stored understand where those recordings end up.
In other words, the practical response here is less about changing settings (SharePoint controls already govern OneDrive sharing) and more about cleaning up what has accumulated.
Microsoft Teams
Every team in Microsoft Teams is backed by a SharePoint site, and the files visible on the Files tab in any channel are SharePoint files, subject to SharePoint sharing and permission rules. Private channels each get their own separate SharePoint site with their own separate permissions. The sharing defaults on all of these sites are inherited from your organization’s SharePoint settings.
Channel meeting recordings are stored in the team’s SharePoint site, so their access follows the channel’s permissions. Non-channel recordings go to the organizer’s OneDrive, as covered above. Either way, Copilot can summarize them.
There is also a less obvious detail worth knowing about. Microsoft notes that in some cases the Channel Agent in Teams can summarize protected content for an authorized user even when other people in the same channel can’t open it themselves. The requesting user is warned, but a warning is easy to skim past in the heat of a busy channel thread, and once the summary posts, what’s in that file is in front of everyone in the conversation.
From a practical standpoint, the fixes for Teams overlap heavily with SharePoint (since that is where the files actually live), but there are a few Teams-specific things worth checking:
- Audit which teams are set to Public and whether that is intentional. Any Public team’s content is discoverable by every employee, and by extension, by their Copilot.
- Review who has permission to create new teams. Unrestricted team creation leads to sprawl, and every new team means a new SharePoint site with inherited defaults that may be too broad.
- Check external access settings. The default Teams configuration allows users on external domains to initiate chats and meetings with your internal users, which is fine when intended but worth tightening if your organization handles sensitive data.
The bottom line is that if your SharePoint defaults are wide open, your Teams file permissions are too.
Outlook and Exchange
Copilot in Outlook works with primary mailboxes on Exchange Online and respects existing mailbox permissions.
In practice, many organizations give certain employees access to other people’s mailboxes. An executive assistant might have Full Access to their boss’s inbox so they can manage scheduling and correspondence. A finance team lead might have delegate rights to a shared departmental mailbox. A colleague covering for someone on leave might be granted temporary access that never gets revoked. These are all common, legitimate setups, and Copilot inherits every one of them. If a user can read a mailbox, Copilot can summarize its contents for them.
That is fine when the access is current and intentional, but it becomes a problem when permissions granted for a specific reason a long time ago are still active today. A quick mailbox permissions audit before rollout can prevent most of these issues:
- Before Copilot goes live, it is worth pulling up a list of every mailbox that has delegate or Full Access permissions assigned and asking whether each one is still needed.
- Pay particular attention to executive mailboxes, shared departmental mailboxes like hr@ or finance@, and any access that was granted on a temporary basis but never cleaned up.
While you are in there, it is also worth checking for automatic forwarding rules that send mail to external addresses. That is not a Copilot-specific issue, but it is the kind of stale configuration that tends to surface during the same review, and Microsoft flags it as a security risk for good reason.
Get Ready for Copilot Now
Every one of the steps described in this article can make your Microsoft 365 environment more secure and better governed right now, regardless of whether Copilot is on your roadmap today or six months from now. And when you do finally flip the Copilot switch, you will do so in an environment you understand, working from current, correctly-scoped data instead of whatever happens to be lying around.
Getting the environment ready is one half of a safe rollout. The other half is how your team actually uses the tool, which is where a clear AI acceptable use policy earns its keep.
If you are not sure where your environment stands or want help prioritizing what to fix first, schedule a meeting with our team.