Microsoft announced Microsoft 365 Copilot on March 16, five days ago, in a keynote that had to share the news cycle with a GPT-4 release that was itself only two days old. The pitch: put a large language model inside Word, Excel, PowerPoint, Outlook, and Teams, ground its answers in your organization's own mail, chat, meetings, and documents through something Microsoft is calling the Semantic Index, and expose all of it through a new cross-app interface called Business Chat. On the strength of the demo video, this is the most consequential thing Microsoft has shown since Teams went from a Slack competitor to critical infrastructure overnight in 2020. As of this morning, it is running in exactly zero of the tenants we operate.
That gap between the keynote and the tenant is this whole note. Microsoft has said early access starts with roughly twenty customers "in the coming weeks." There is no general availability date, no published price, and no admin center toggle anywhere in Microsoft 365 that turns any of this on. Every client call we have taken this week has opened with some version of "can we get this now" and closed somewhere more useful: a conversation about SharePoint sharing links, guest accounts left over from a 2021 vendor project, and who still holds Global Administrator eight months after changing roles. Copilot's real risk this month has nothing to do with the model. It has to do with permissions your tenant already granted, which Copilot did not create and is not going to fix for you.
What Microsoft 365 Copilot actually shipped on March 16
Nothing shipped. That is worth saying plainly before the rest of this note, because the coverage this week has blurred vision and availability into one thing. What Microsoft showed was a set of five product surfaces layered with a common assistant: Word drafting from a prompt or an outline, Excel explaining a dataset and proposing formulas in plain language, PowerPoint turning a Word document into a deck with speaker notes, Outlook summarizing a thread and drafting a reply in your voice, and Teams catching a meeting up on what it missed and pulling action items out of the transcript. Business Chat sits across all five and Microsoft Graph, so a prompt like "what's the status of the Fairmont proposal" can pull from a deck, an email thread, and a chat message without you opening any of the three.
The model underneath is GPT-4, which is notable mostly for timing: had Microsoft announced this a month earlier, it would have shipped on GPT-3.5, the same model behind ChatGPT and the new Bing since February. GPT-4 brings a materially larger context window and, per OpenAI's own release notes, meaningfully fewer factual misses. The mechanism Microsoft is leaning on hardest, though, is the Semantic Index, described as a layer that grounds prompts in your tenant's Graph content rather than the model's frozen training data. That is the feature actually worth tracking, and it is also the one Microsoft has explained the least. We do not yet know indexing latency, how freshly it reflects a file edited an hour ago, or what happens to grounding when a site's permissions change mid-session. Microsoft also mentioned a plugin model for connecting Copilot to line-of-business systems, structurally similar to the plugin approach OpenAI has been previewing for ChatGPT.
Twenty customers, in the coming weeks, no price, no date. That is the entire availability story as of today, and it is the correct amount of information to plan around: not enough to build a rollout, plenty to start the hygiene work underneath it.
Permissions are the product
Buried in the announcement materials is a sentence that matters more than anything about the model: Copilot answers using only what the requesting user could already see, enforced through the same Microsoft Graph permission checks that govern SharePoint, OneDrive, Teams, and Exchange today. There is no new Copilot-specific access model. It does not grant anyone new visibility into anything. That is the correct design decision, and it is also the reason this announcement changed our week more than GPT-4's release two days before it did.
Today, finding a misplaced file requires knowing it exists, guessing at keywords, and being motivated enough to dig through a search box that most users have given up trusting. A natural-language assistant that answers "what's our current thinking on the Meridian renewal" by quoting a spreadsheet shared with "Anyone with the link" six months ago, because that spreadsheet happens to be the most relevant document a user can see, has not bypassed any control. It has just made finding the spreadsheet require zero skill and zero motivation. Nothing about access control changed. Retrieval got dramatically better at using access that was already granted, correctly or not.
We would rather clients heard this from us in March, with no live product to point at, than from an angry business unit lead in October pointing at a Copilot answer that quoted last year's compensation planning sheet.
The oversharing time bomb sitting in most SharePoint tenants
Every tenant more than a few years old carries the same handful of oversharing patterns, and none of them have been urgent enough to fix because finding them has always required looking.
- Sharing links set to "Anyone" during a default tenant configuration years ago, never revisited after Microsoft tightened its own default guidance
- OneDrive accounts belonging to staff who left the company, still fully accessible to a former manager or team "just in case," years after the departure
- Teams sites spun up for a project that closed in 2020, never archived, membership never pruned, still discoverable by anyone who can browse SharePoint
- Guest accounts added for a single vendor engagement that ended a year or two ago and were never removed from the tenant's guest list
At a regional bank we support, a spot check the Friday after the keynote turned up a shared document library holding vendor contract drafts, still reachable through a sharing link created before some of the vendor relationships in it had even been signed. Nobody had done anything wrong. Nobody had looked, either, because looking has never been free. A fluent question-answering layer removes the cost of looking, for anyone with a keyboard and a reason to ask.
The prep-before-Copilot checklist
None of the following requires Copilot access, a license, or a date from Microsoft. All of it is available in the tenant you already run, this afternoon.
| Before your next Copilot conversation | Why it matters now |
|---|---|
| Oversharing review on SharePoint and OneDrive | Copilot will surface whatever the sharing settings already allow |
| Sensitivity labels on high-value libraries | Labels give both a policy hook and a visible cue before AI grounding arrives |
| Guest account cleanup | Stale guests are exactly the accounts Copilot will treat as legitimate |
| Privileged account reduction | A careless prompt from an over-privileged account has a wider blast radius |
Start the oversharing review with the sharing capability set at the site level, not the tenant default, because tenant defaults get overridden site by site and nobody remembers which sites diverged:
Connect-SPOService -Url https://contoso-admin.sharepoint.com
Get-SPOSite -Limit All |
Select-Object Url, SharingCapability, StorageUsageCurrent |
Where-Object { $_.SharingCapability -ne "Disabled" } |
Export-Csv .\sharing-audit.csv -NoTypeInformation
Pair that with a guest and privileged-role export from Azure AD. Both of these are five-minute scripts that most of our clients have never run, on tenants that are eight or ten years old:
Connect-AzureAD
Get-AzureADUser -Filter "userType eq 'Guest'" |
Select-Object DisplayName, UserPrincipalName, CreatedDateTime |
Sort-Object CreatedDateTime
Get-AzureADDirectoryRole | Where-Object DisplayName -eq "Global Administrator" |
Get-AzureADDirectoryRoleMember |
Select-Object DisplayName, UserPrincipalName
The output of both scripts is usually the same reaction: a long silence, then a request for a bigger project than the one that was originally scoped. Good. That is the correct reaction, five days after this announcement and however many months before Copilot reaches any of these tenants.
Our pilot posture until early access lands
We are not filling out early-access forms for clients this week, and we are actively talking a few out of doing it themselves before the hygiene work above is underway. If a client does land one of the twenty slots, we want the tenant that gets the demo to be the clean one, not the one that turns into an incident write-up because Copilot faithfully quoted something it should never have been able to reach.
What we are doing instead: identifying a candidate pilot boundary now, one division's SharePoint hub rather than the whole tenant, so there is a defined content set ready when access actually opens. Running Azure AD access reviews against that boundary's guest and privileged accounts so attestation happens on a schedule rather than never. Extending Microsoft Purview sensitivity labels and DLP policies to cover the content types that should not be summarized for anyone, including an authorized user, through a chat interface, such as board financials, HR investigations, or anything under legal hold. And separating, in every client conversation, Microsoft 365 Copilot from the Azure OpenAI Service pilots several clients already have running in-tenant since January's general availability. They are related and they are not the same thing, and conflating them is how a budget conversation starts from the wrong number.
Twenty companies get to beta test this for Microsoft over the coming weeks. We would like whichever of our clients ends up among them to be memorable for the pilot going well, not for being the cautionary tweet.
If you're facing this
If your tenant has not had a sharing-link or guest-account review in longer than anyone can remember, do not wait for a Copilot access date to start one. Bring us your SharePoint sprawl, your guest list, and your Global Administrator roster, and we will help you turn "we should look into that" into a scoped project with an owner and a deadline before the product that makes all of it visible actually arrives.