Aug 11, 2026

How to Connect Multiple Outlook Accounts to Codex

Codex has no built-in Outlook connector, so reaching two mailboxes is a question of which MCP server you register. Authorize each Microsoft identity in Carly, add one MCP server, and the Codex CLI can query or act 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.

Codex is a coding agent. This setup is genuinely useful for scripted mailbox work from a terminal; recurring triage and follow-up belong in a Carly workflow that runs with nothing open.

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 accepts personal Outlook.com addresses and Microsoft 365 work accounts alike, and each tenant approves independently, so one company’s administrator declining does not block 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 Codex to reach through the same connector.

2. Register Carly as an MCP server

codex mcp add carly --url https://carlyassistant.com/mcp/

Servers added through the CLI land in ~/.codex/config.toml at user scope. The hand-written equivalent:

[mcp_servers.carly]
url = "https://carlyassistant.com/mcp/"

A trusted project can keep its own .codex/config.toml if you would rather scope the server to a single repository.

Then authenticate:

codex mcp login carly

That opens the browser OAuth flow. Sign in to the Carly workspace holding the Outlook accounts. Codex supports OAuth and bearer tokens against remote HTTP MCP servers, so no secret needs to sit in a config file.

Verify before moving on:

codex mcp list

Why one server beats one per mailbox

Wiring Outlook into Codex usually means a third-party MCP provider and your own OAuth app. That is tolerable for one mailbox. Three mailboxes across two employers means three server entries, three sets of Microsoft credentials, and no shared way to say which one you mean.

Third-party Outlook MCP versus Carly in Codex

Need	Per-account MCP server	Carly MCP server
Reach one mailbox	Yes	Yes
Reach several mailboxes	One server per account	One server, all accounts
Address a specific mailbox in a prompt	No shared convention	Yes, by email address
Register your own Microsoft app	Often required	No
Mix personal Outlook.com with work tenants	Usually separate setups	Yes, in one place
Add another tenant later	New server entry	No config change
Keep the work running outside Codex	No	Yes

Carly turns several Microsoft logins into one addressable mail toolset for Codex. Carly offers free Zapier-style workflows; AI agents start at $35/month.

Quick fixes when a mailbox does not appear

Problem	Fix
Tools do not show up	Start a new Codex session after adding the server
`codex mcp login` never completes	Finish the browser OAuth flow, then rerun `codex mcp list`
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
Codex queries the wrong mailbox	Use the full address and require source attribution

Frequently asked questions

Does Codex have a native Outlook integration?

No. Codex reaches Outlook through the Model Context Protocol, so what it can do depends on the MCP server you register.

How many Outlook accounts can this reach?

As many as you authorize in Carly. Codex talks to one server, so the mailbox count is a Carly setting.

Can I mix a personal Outlook.com address with work accounts?

Yes. Connect each Microsoft identity to Carly and label every address with a clear Personal or Work role.

Ready to automate your busywork?

Carly schedules, researches, and briefs you—so you can focus on what matters.

See what people say

"Before Carly, I relied on a Calendly link, but the whole process felt impersonal and not very professional. Carly changed that by handling all the back-and-forth, so I'm no longer stuck in endless email threads trying to line up schedules.

Now Carly reaches out to candidates, shares my real-time availability, lets them pick a slot, then sends a Zoom link and drops it straight into my calendar. She sends reminders to both of us before each call, which has significantly reduced no-shows and last-minute confusion.

On top of scheduling, Carly acts like a full executive assistant, sending me my schedule the night before so I can prepare for each call. It reminds me of the old x.ai assistant, but Carly is noticeably smarter, faster, and better suited to my healthcare recruitment business."

Gus Ibrahim, Founder & Director, IHR