Outlook Mail

A Model Context Protocol server that lets Claude, Codex and any other MCP client read, search, send and organize your Outlook / Microsoft 365 / Outlook.com mail through the Microsoft Graph API.

🔭 Overview

outlook-mcp runs locally over stdio. It signs in with the OAuth device code flow (no client secret, no redirect URI), stores the refresh token in your OS keychain (or a local file only you can read), and talks to Microsoft Graph with plain fetch.

✨ Features

• 📂 Browse folders, list and search messages (KQL), read bodies as sanitized plain text
• 📎 List and download attachments safely into a configured directory
• ✉️ Send mail, create drafts, reply, reply-all and forward (local attachments up to 150 MB; files of 3 MB or more are uploaded in chunks)
• 🗂️ Move, mark read/unread, flag and delete messages, one at a time or in bulk (ids)
• 📰 Find newsletters, unsubscribe from them and block unwanted senders with inbox rules
• 🔒 Read-only mode that removes every mutating tool
• 🔁 Automatic retry with Retry-After / exponential backoff for throttling (429/503/504)
• 🧾 Logs only to stderr; never logs tokens or message bodies

📋 Requirements

• Node.js 24 (LTS) or newer
• A Microsoft account (personal works out of the box; work or school needs your own Azure app)

🚀 Quick start

No terminal sign-in and no Azure setup needed. You only need Node.js 24+.

Claude Code

claude mcp add outlook --scope user -- npx -y @pepebits/outlook-mcp

Claude Desktop

Add to claude_desktop_config.json and restart Claude Desktop:

{

"mcpServers": { "outlook": { "command": "npx", "args": ["-y", "@pepebits/outlook-mcp"] } } }

Codex (OpenAI)

codex mcp add outlook -- npx -y @pepebits/outlook-mcp

Or add it to ~/.codex/config.toml (shared by the Codex CLI and IDE extension):

[mcp_servers.outlook]

command = "npx" args = ["-y", "@pepebits/outlook-mcp"]

env = { OUTLOOK_READ_ONLY = "true" }

Run /mcp inside Codex to check that it is connected.

Other MCP clients

Any client that can launch a stdio MCP server works: run npx -y @pepebits/outlook-mcp as the server command.

Sign in

Ask your assistant to *"log in to Outlook"*. The login tool returns a URL and a one-time code: open the URL, enter the code and accept. Prefer a terminal? Run npx -y @pepebits/outlook-mcp auth instead.

By default the server uses the shared outlook-mcp Azure app, which supports personal Microsoft accounts (outlook.com, hotmail, live). The consent screen may show an *unverified publisher* warning. No data passes through any server of ours: the server talks to Microsoft Graph directly from your machine and your tokens stay in the local token cache. For work or school accounts, or to use your own app, see Use your own Azure app.

⚙️ Configuration (.env)

The .env file is optional. Variables are read from .env in the current directory and in the package directory, and real environment variables override it. You can also pass them through your MCP client's env block, e.g. claude mcp add outlook --scope user -e OUTLOOK_TENANT=organizations -e OUTLOOK_CLIENT_ID=your-client-id -- npx -y @pepebits/outlook-mcp.

🔐 Authentication

npx -y @pepebits/outlook-mcp auth      # device code sign-in; prints a URL and a code

npx -y @pepebits/outlook-mcp whoami # silent token + GET /me npx -y @pepebits/outlook-mcp logout # removes accounts and deletes the token cache (keychain entry and file)

You can also sign in without a terminal. Just ask your assistant to *"log in to Outlook"*:

• 🔑 login returns a URL and a one-time code. Open the URL, enter the code and accept; sign-in finishes in the background.
• ✅ auth_status tells you whether you are signed in, still waiting, or signed out.
• 🚪 logout removes the cached account and the token cache (keychain entry and file).

Use login with force: true to sign in again, for example after adding a permission in Azure. If the session is missing or expired, tools return *"Not signed in or session expired. Call the login tool ..."*.

🗝️ Token storage

The refresh token is the most sensitive thing this server holds, so by default (OUTLOOK_TOKEN_STORE=auto) it goes into the operating system keychain instead of a plain file. No native npm dependencies are used; the server calls the OS tools directly:

• Migration: if a cache file exists and the keychain is still empty, it is imported into the keychain and the file is deleted.
• Fallback: in auto mode, if the keychain cannot be used at runtime the server falls back to the file and logs a warning. OUTLOOK_TOKEN_STORE=keychain never falls back and fails instead; file never touches the keychain.
• Secrets stay out of process listings: on Linux secret-tool reads the secret from stdin. security add-generic-password only accepts the password as a command-line argument (visible in ps to other local processes), so on macOS the commands are fed to security -i over stdin instead. That interface truncates lines at about 4 KB, so the cache is stored base64 encoded across a few small keychain items ( #0, #1, ...).
• logout (tool and CLI) removes the keychain entry as well as the file.
• On macOS the first access from a different binary may show a Keychain prompt; click *Always Allow*.

🛠️ Use your own Azure app (optional)

By default outlook-mcp uses the shared outlook-mcp Azure app, which works with personal Microsoft accounts only. Register your own app if you need work or school accounts or simply prefer to use your own. Then set OUTLOOK_CLIENT_ID (and OUTLOOK_TENANT, see below).

Step by step

1. Open portal.azure.com and go to Microsoft Entra ID -> App registrations -> New registration.
2. Give it a name (for example outlook-mcp).
3. Under Supported account types choose:

• Personal Microsoft accounts only (Outlook.com, Hotmail, Live), or
• Accounts in any organizational directory and personal Microsoft accounts (both).
• For work/school only, pick an organizational option.

1. Leave Redirect URI empty and click Register.
2. In the left menu go to Manage -> Authentication -> Settings tab, set Allow public client flows to Yes and save.
3. Go to Manage -> API permissions. User.Read is already granted by default. Click Add a permission -> Microsoft Graph -> Delegated permissions and add:

• 📬 Expand the Mail group and tick Mail.ReadWrite and Mail.Send.
• ⚙️ Expand the MailboxSettings group and tick MailboxSettings.ReadWrite (needed for inbox rules and block_sender).
• 🔑 Expand the OpenId permissions group and tick offline_access.

Then click Add permissions. No admin consent is needed for personal accounts.

💡 If you upgrade from 0.1.0, add MailboxSettings.ReadWrite in Azure and run login with force: true (or npx -y @pepebits/outlook-mcp auth) again.

💡 The Azure portal may be shown in your language, so labels can differ slightly (e.g. *Administrar* -> *Autenticación* -> *Configuración*, *Permisos de OpenId*).

1. From the Overview page copy the Application (client) ID. This is your OUTLOOK_CLIENT_ID.

🏢 Work or school accounts: set OUTLOOK_CLIENT_ID to your app and OUTLOOK_TENANT=organizations (or your tenant GUID). Your organization may require admin consent for the mail permissions.

🧰 Tools reference

| bulk_action | yes | Apply delete, move, archive, markRead, markUnread, flag or unflag to every message matching a query (KQL) or filters (folderId, from, `si