How to Connect Multiple Outlook Accounts to Le Chat
One Le Chat conversation can search and act across every Outlook mailbox you own once Carly is holding them, including mailboxes in different Microsoft tenants. Authorize each Microsoft identity in Carly, add one custom MCP connector in Le Chat, and the conversation addresses 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.
What one conversation 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.
Why the tenant boundary is the thing to design around
Microsoft mailboxes are not just several logins. A consultant with a personal Outlook.com address and mailboxes at two client organizations is dealing with three separate consent boundaries, each governed by a different administrator, each revocable independently. That is the structural problem, and it does not go away by signing in somewhere else.
Carly holds each Microsoft identity as its own authorized connection and exposes all of them through a single server that addresses any mailbox by email address. Adding a fourth tenant later is a Carly setting rather than a new piece of plumbing, and one tenant revoking access leaves the others working.
The built-in connectors hold one account per provider. ChatGPT, Claude, and Gemini each authorize a single Google identity, and connecting a second one replaces the first rather than adding to it. Switching inboxes means disconnecting and reauthorizing, which is why "personal and work" is still two sessions rather than one.
1. Give each Outlook account a role
Using fictional addresses:
| Address | Role |
|---|---|
fictional.tomas.beckett@outlook.com | Personal |
fictional.tomas.beckett@pepsi.com | Main Company |
fictional.tomas.beckett@cisco.com | Client |
Use the role in ordinary questions and the full address before anything that writes.
2. Connect every Outlook account to Carly
- Sign in at carlyassistant.com.
- Open carlyassistant.com/integrations.
- Find Outlook and click Connect.
- Sign in with the first Microsoft identity and approve the permissions.
- Confirm the connected address in Carly.
Repeat for every other mailbox. Microsoft will reuse whichever session you are already signed into, so sign out or use a private window between authorizations and check the full address each time.
Work accounts governed by an administrator may need approval before the connection completes. Each tenant decides separately, so approval at one employer says nothing about the other.
3. Add Carly to Le Chat as a custom MCP connector
This is the step that makes the mailboxes reachable. Le Chat splits connectors into featured connectors you click to authorize, a directory of partner MCP servers, and custom MCP connectors, which let you point Le Chat at any remote MCP server you trust. Carly goes in through the third route.
Open Le Chat’s Connectors settings, choose the option to add a custom MCP connector, and give it:
- Name:
Carly - Server URL:
https://carlyassistant.com/mcp/
Carly’s server is hosted and authorizes over OAuth, so there is nothing to deploy and no key to paste. Complete the sign-in to the Carly workspace holding your mailboxes. Carly’s mail, calendar, and workflow tools then appear alongside your other connectors, and because Mistral registers connectors centrally, the same connection is available across Le Chat and AI Studio rather than needing separate setup in each.
4. Test every mailbox read-only first
One account per question to start:
In
fictional.tomas.beckett@pepsi.com, list the sender and subject of the five newest unread messages. Do not change anything.
In
fictional.tomas.beckett@cisco.com, find the newest thread containing “statement of work.” State the source account and do not draft.
Then across tenants, which is the question that has no other answer:
Search both example work mailboxes for “renewal” in the last 45 days. Include the full source address in every row.
5. Reuse this routing prompt
Treat
fictional.tomas.beckett@outlook.comas Personal,fictional.tomas.beckett@pepsi.comas Main Company, andfictional.tomas.beckett@cisco.comas Client. Always state the target address before changing data. Ask before sends, moves, deletes, or category changes.
Then name the target in each action:
Draft the reply from
fictional.tomas.beckett@pepsi.com. Do not send yet.
File that thread under Contracts in
fictional.tomas.beckett@cisco.comonly.
Send the approved reply from the mailbox that received the original message.
Two employers in one conversation is exactly where a misrouted send is expensive. Keep approvals on until the routing has proved itself.
The part that outlives the conversation
Conversations end. The mail does not. Triage at 8am, the follow-up on the proposal nobody answered, the weekly client summary, the invoice that has to reach the bookkeeper: all of it recurs, and none of it should wait for you to open a tab.
That work belongs in a Carly workflow or a Carly agent. Carly’s triggers are keyed per mailbox, so a rule can fire on mail arriving at the client address and stay silent on the personal one, and it keeps running while your laptop is shut. Le Chat stays what it is good at: somewhere to ask sharp questions across everything, with the repetitive half already handled underneath.
One connector versus one mailbox at a time
| Need | A per-account mail connector | Carly through custom MCP |
|---|---|---|
| Read and act in one mailbox | Yes | Yes |
| Hold mailboxes in two tenants | Consent and reconnect per account | Yes, all at once |
| Answer a question spanning two employers | Not in one conversation | Yes |
| Address a specific mailbox in a prompt | No shared convention | Yes, by email address |
| Add a fourth tenant later | Another consent chain to manage | No config change |
| Keep the work running between conversations | No | Yes |
Carly gives Le Chat one account-aware mail toolset instead of a connector you keep re-pointing. Carly offers free Zapier-style workflows; AI agents start at $35/month.
Quick fixes when a mailbox does not appear
| Problem | Fix |
|---|---|
| Carly’s tools are missing in Le Chat | Reopen the connector and let it refetch the tool list |
| The connector will not authorize | Finish the OAuth sign-in in the browser tab Le Chat opens |
| Microsoft reconnected the same mailbox twice | Sign out or use a private window, then reconnect |
| A tenant blocks authorization | Ask that tenant’s administrator to approve Carly |
| Le Chat queries the wrong mailbox | Use the full address and require source attribution |
| A send went from the wrong account | Add the routing prompt above and keep approvals on |
Frequently asked questions
Can this reach mailboxes in two different Microsoft tenants?
Yes. Each Microsoft identity is authorized separately inside Carly, so the tenants stay independent while Le Chat still sees one connector. Each tenant’s administrator approves its own mailbox.
How many Outlook accounts can this reach?
As many as you authorize in Carly. Le Chat connects to one server, so the mailbox count is a Carly setting rather than a Le Chat one.
What about a shared or delegated mailbox?
Connect the account that has been granted access to it, then name the shared address in your prompt. Whether the delegation is permitted at all is a decision your Microsoft administrator makes.
Can the same setup cover Gmail?
Yes. Connect Gmail accounts in the same Carly account and one conversation reaches both providers. The multiple Gmail accounts in Le Chat guide covers that side.
Related: Multiple Gmail accounts in Le Chat · Multiple Outlook accounts in Claude Code · Best AI assistants for multiple Microsoft accounts · Outlook MCP · What is MCP
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