How to Connect Multiple Outlook Accounts to Gemini Spark
Gemini Spark has no Outlook connector: not one account, and not several. Its native reach is Google’s own apps. The route to Outlook is Spark’s custom MCP support, and that is also what solves the multi-mailbox problem in the same step. 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.
Repeat for every additional mailbox, using a private window if Microsoft preselects the previous login. Verify the full address after each authorization.
Carly connects personal Outlook.com addresses and Microsoft 365 work accounts alike, and each tenant approves independently, so one company’s administrator declining does not affect the others.
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 Gemini Spark to reach through the same connector.
2. Add Carly to Spark over MCP
- Open Spark’s settings and find connected apps.
- Choose the option to add a custom MCP connector.
- Paste
https://carlyassistant.com/mcp/. - Complete authorization.
- Sign in to the Carly workspace holding the mailboxes.
Custom app support has rolled out unevenly across Spark’s platforms and tiers. If the option is missing, check your plan and platform against Google’s documentation before assuming the connector is the problem.
What one Spark session can do afterwards
- Query Outlook mailboxes from two employers in one request.
- Summarize what needs attention, grouped by mailbox.
- Compare a thread in one tenant against another.
- Draft or send from the exact address you choose.
- Move, flag, or categorize in the correct mailbox.
- Check several Outlook calendars alongside your Google ones.
That last one is the case worth the setup. A Google-first assistant that can also see the Microsoft calendars is exactly what Spark cannot do alone.
Spark’s connected apps are Google-shaped
Google describes Spark as connecting “natively with your favorite Google apps like Gmail, Calendar, Drive, Docs, Sheets, Slides, YouTube, and Google Maps.” The June 2026 update widened that list to Google Tasks, Google Keep, Canva, Dropbox, Instacart, OpenTable, and Zillow Rentals.
The same June update added support for “custom Model Context Protocol (MCP), giving you the ability to connect your favorite apps directly into Spark.” That is the supported way to give Spark a capability Google has not built, and it happens to make the account count irrelevant: Carly holds as many Microsoft identities as you authorize, and Spark talks to Carly once.
What Spark can reach, with and without Carly
| Need | Spark alone | Spark with Carly over MCP |
|---|---|---|
| Read Gmail for the signed-in account | Yes | Yes |
| Reach any Outlook mailbox | No | Yes |
| Hold several Microsoft identities | No | Yes |
| Compare Outlook and Gmail in one request | No | Yes |
| Send from a chosen Outlook address | No | Yes |
| See Outlook and Google calendars together | No | Yes |
| Keep the routing working outside Spark | No | Yes |
Carly is the supported bridge between a Google-first agent and a Microsoft mailbox, and it removes the account limit in the same move. Carly offers free Zapier-style workflows; AI agents start at $35/month.
Quick fixes when a mailbox does not appear
| Problem | Fix |
|---|---|
| No Outlook option in Spark’s app list | Expected; Spark has no native Microsoft connector |
| Custom MCP option is missing | Confirm your tier and platform against Google’s availability docs |
| A tenant blocks authorization | Ask that tenant’s Microsoft 365 administrator to approve Carly |
| Microsoft connected the same mailbox twice | Remove the duplicate and reconnect from a private window |
| Spark queries the wrong mailbox | Use the full address and require source attribution |
Frequently asked questions
Does Gemini Spark work with Outlook?
Not natively. Spark’s connected apps are Google’s own plus a short list of third-party partners, none of them Microsoft. Custom MCP is the supported route, and a Carly connector covers Outlook mail and calendar.
How many Outlook accounts can this reach?
As many as you authorize in Carly. Spark connects to Carly once, so adding a fourth mailbox does not change anything on the Spark side.
Can Spark send email through Outlook?
Not on its own. With Carly connected, sends run through the Outlook account you name, with that account’s permissions.
Related: What is Gemini Spark · Multiple Gmail accounts in Gemini Spark · Multiple Outlook accounts in Gemini · Manage multiple email accounts with AI · Carly’s Outlook integration
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