How to Connect Multiple Outlook Accounts to Copilot
Microsoft Copilot cannot answer a question that spans two Outlook mailboxes, and connecting every account to Carly is the way around it. Microsoft does ship something called multiple account access, but it is a licensing bridge for documents rather than mailbox reach. Authorize each Outlook identity in Carly and one instruction can search, draft, or file in whichever mailbox you name. The same Carly account holds your Gmail inboxes and every calendar on both sides, so you set this up once for all of it.
1. Add your Outlook accounts to Carly
- Sign in at carlyassistant.com.
- Open carlyassistant.com/integrations.
- Find Outlook, click Connect, and authorize the account.
- Click Connect again for the next one, and keep going for as many accounts as you want.
Personal Outlook.com addresses and work tenants connect the same way and sit side by side. If a Microsoft 365 tenant requires administrator consent, ask the tenant administrator to approve Carly, then finish authorization.
Carly connects to thousands of apps, so while you are on that page you can add your calendars, files, CRM, and anything else you want Copilot to reach through the same connector.
2. Choose how Copilot reaches Carly
Copilot has no box where an ordinary user pastes a connector URL, on either SKU. Consumer Copilot at copilot.com ships a fixed connector list covering OneDrive, Outlook.com, Google Drive, Gmail, Calendar, and Contacts, and its support page never mentions MCP at all. Microsoft 365 Copilot, the paid work SKU, accepts an MCP Base URL only from an administrator. That is Microsoft’s connector model rather than a gap on Carly’s side, and it leaves three honest routes.
You work with Carly directly. The accounts you connected at step 2 are usable immediately, and multi-account routing plus event triggers are the whole point of them. Most readers stop here.
A maker adds Carly in Copilot Studio. This is the Microsoft-side route that actually fits Carly. Go to Tools → Add a tool → New tool → Model Context Protocol, then supply a server name, a description, and https://carlyassistant.com/mcp/ as the server URL, choosing None, API key, or OAuth 2.0 for auth. Only Streamable transport is supported; SSE was dropped in August 2025. It needs a work or school account and a paid licence, the trial cannot publish the agent, and what you get is a separate agent rather than Copilot Chat.
An administrator adds a federated connector, with one caveat. In the Microsoft 365 admin center, go to Copilot → Connectors → Gallery → Create a new connector, then under Connect to MCP server select Add and fill in the display name and Base URL. It needs the Global Administrator or AI Administrator role plus a registered Entra SSO or OAuth 2.0 application. Microsoft requires these connectors to expose read-only tools and documents federated connectors as read-only, so an admin taking this route gets a read slice rather than sending, drafting, or filing. Federated connectors reached general availability in June 2026 and admin center management shipped in July 2026.
If none of those shapes fits your team, the API and bring-your-own-key path runs through the Carly team. Book a call to scope it.
What one chat can do afterwards
- Search two employers’ mailboxes in the same question.
- Compare threads sitting in different Microsoft tenants.
- Build a morning briefing grouped by account.
- Draft or send from the exact address you name.
- Move, categorize, or flag in the correct mailbox.
- Read several calendars while writing to only one.
Nothing is merged and nothing is forwarded. Each mailbox keeps its own credentials, and Carly keeps every account individually addressable.
What multiple account access actually does
Microsoft’s multiple account access documentation describes a licensing bridge: in apps that support signing in with more than one account, “users can use their Microsoft 365 Copilot access from one account on documents from a different account.” It covers Word, Excel, PowerPoint, Outlook, and OneNote on desktop and mobile, and it is always disabled for GCC, GCC High, DoD, and 21Vianet customers.
| Copilot capability | Through multiple account access |
|---|---|
| Access the organization’s Microsoft Graph | No |
| Ask about the currently open document and make edits | Yes |
| Ask about other documents that are not the open one | No |
| Ask questions answered by web search | Yes |
Where each tool fits
| Need | Copilot with multiple account access | Carly |
|---|---|---|
| Draft and edit inside the open document | Yes | Not the job |
| Use a license from another account on a file | Yes | Not the job |
| Search across several mailboxes at once | No | Yes |
| Compare threads from different tenants | No | Yes |
| Send from a chosen connected account | The active identity | Yes, with that account’s permissions |
| Reach the organization’s Graph this way | No | Not applicable |
| Keep the routing running on a schedule | No | Yes |
Copilot stays the in-document assistant. Carly holds the mailboxes, routes by address, and fires on the event rather than on a prompt: the invoice lands, it is filed against the right client, the renewal date goes on a calendar, and the account owner gets the summary. Free Zapier-style workflows; AI agents from $35/month. Connect it on the integrations page, or start with Outlook.
Quick fixes
| Problem | Fix |
|---|---|
| Microsoft reconnected the same address twice | Remove the duplicate and reconnect with Use another account |
| Tenant blocks authorization | Ask the Microsoft 365 administrator to approve Carly |
| Multiple account access is unavailable | Check whether the tenant is GCC, GCC High, DoD, or 21Vianet, where it is always disabled |
| An answer cites the wrong mailbox | Use the full address and require source attribution |
| A shared mailbox never appears | Confirm the signed-in account has permission to it, then reconnect |
| No connector box anywhere in Copilot | Expected on both SKUs; the MCP surface is admin and maker gated |
Frequently asked questions
Can Copilot read two mailboxes at once?
No. Microsoft’s multiple account access is scoped to documents and licensing rather than cross-mailbox questions, and its capability table rules out the organization’s Graph and any document that is not currently open. Connecting each mailbox to Carly is what makes a question spanning several accounts answerable.
Can I paste a connector URL into Copilot myself?
Copilot exposes no paste-a-URL box to ordinary users on either SKU. An administrator can add an MCP Base URL in the Microsoft 365 admin center, and a maker can add one in Copilot Studio, which is the route that carries write actions.
Does this apply to Outlook.com and Microsoft 365 together?
Yes. Carly authorizes personal Outlook.com addresses and Microsoft 365 tenants the same way, and they can be connected at the same time.
Does anything get merged into one inbox?
No. Every mailbox keeps its own credentials, and each read or action is routed to the address you name.
Related: Microsoft Copilot alternatives · Multiple Outlook accounts in ChatGPT Work · Multiple Outlook accounts in Claude Cowork · Manage multiple email accounts with AI · Carly’s Outlook integration
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