MCP server for Microsoft Outlook Web. No app registration required.

Give any MCP client (Claude, Cursor, Devin, ...) read and write access to your Outlook mail, calendar, contacts, and the org directory. It works by reusing your existing Outlook Web session, the same way @shayanline/msteams-mcp reuses the Teams web session: you sign in once in a browser, then tokens are cached and refreshed automatically.

Most Outlook MCP servers make you register an Azure AD application, grant admin consent, and manage client secrets. This one needs none of that. It reuses Outlook Web's own first party client ID, so your access is exactly what your account already has, and nothing leaves your own machine.

• Zero setup auth. No Azure app registration, no admin consent, no client secrets. Sign in once in a browser; tokens are cached encrypted and refreshed silently after that.
• Over 50 tools across mail, calendar, contacts, people, the org directory, and your own account settings.
• Safe by default. Email bodies are sent as HTML so line breaks always render, and the draft tools let you compose and review before anything is sent.
• Scheduling and availability. Read free/busy, find meeting times across attendees, and check who is out of office.
• Cross platform. macOS, Linux, and Windows, with automatic browser detection.

Microsoft Outlook Web (OWA) uses MSAL to store OAuth tokens in localStorage. This server:

1. Opens a browser to outlook.office.com via Playwright
2. Extracts the MSAL token cache from localStorage, using OWA's own first party client ID (9199bf20-a13f-4107-85dc-02114787ef48)
3. Caches the access token, refresh token, and session state in ~/.msoutlook-mcp-server/ (AES-256-GCM encrypted)
4. Refreshes tokens automatically using the refresh token (HTTP, no browser) or a headless browser as fallback

No Azure app registration. No admin consent. No client secrets. Your access is limited to what your account can already do.

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

Then run outlook_login from your MCP client. On first use a browser opens so you can sign in; after that, logins are silent and no browser appears. Do not close the window manually, it closes itself once you are signed in.

• HTML by default. outlook_send_email, outlook_create_draft, and the reply/forward tools render their body as HTML, so use <br>, <br><br>, and <ul><li> for structure. Plain text is still accepted: its newlines are converted to <br> automatically, so a message never arrives as one collapsed block.
• Review before sending. Prefer the draft tools (outlook_create_draft, outlook_create_reply_draft, outlook_create_forward_draft) so you can review or edit with outlook_update_draft and then send with outlook_send_draft. The immediate tools (outlook_send_email, outlook_reply, outlook_forward) send straight away.
• Presence caveat. outlook_get_availability reports free/busy and out of office, which is what Outlook can read. The live Teams presence dot (Available / Away / DoNotDisturb) needs a Teams token and is not available here.

• Recurrence. outlook_create_event and outlook_update_event take an optional recurrence object that maps to Microsoft Graph's patternedRecurrence (a pattern plus a range). Supported patterns: daily, weekly (with days_of_week), absoluteMonthly (day_of_month), relativeMonthly (e.g. last Friday via index + days_of_week), absoluteYearly (month + day_of_month), and relativeYearly. Set interval for "every N" (e.g. every 3 weeks). The range ends with endDate (end_date), numbered (count), or noEnd, and carries the recurrence time_zone. range.start_date defaults to the event's start date.
• Reminders. Use reminder_minutes_before_start and is_reminder_on. Graph and Outlook support only one reminder per event, so you cannot set, for example, both a one-month and a one-week reminder on a single event. Mirror the same event into separate calendars if you need several lead times.
• Date window. outlook_list_events uses Graph's calendarView, so a start_date/end_date window genuinely scopes the results and recurring series are expanded into individual instances. When only start_date is given, the window runs a week forward from it.
• Mirroring personal events. show_as (free/tentative/busy/oof/workingElsewhere), categories, and is_private help when copying personal events into a work calendar.

Session files are stored encrypted in ~/.msoutlook-mcp-server/:

• session-state.json: Playwright browser session (cookies + localStorage)
• token-cache.json: Extracted and cached tokens
• browser-profile/: Persistent browser profile for headless refresh

If your session expires, run outlook_login again.

Tokens are refreshed automatically:

1. HTTP refresh (fast, no browser): uses the cached refresh token with OWA's client ID
2. Headless browser refresh: fallback if HTTP refresh fails; opens a headless Edge window to silently reacquire tokens from the saved browser session

• Node.js 20+
• A Chromium based browser: Edge or Chrome (detected automatically from system default)
• A Microsoft 365 work/school account or personal Microsoft account

Cookie import is a best effort optimisation. If it cannot run (e.g. no matching browser installed, Keychain denied), the MCP falls back to opening a headed browser where you sign in once manually, and the session then persists.

• Uses the same auth as the Outlook web client, so your access is limited to what your account can do
• Tokens are encrypted at rest (AES-256-GCM with a machine derived key)
• Uses undocumented internal APIs, which Microsoft may change without notice
• Always confirm email content with the user before sending

A macOS Keychain prompt appears on first login. That is the cookie import reading your browser's session. Click "Always Allow" once and it never prompts again. If you would rather not grant it, set MSOUTLOOK_SKIP_COOKIE_IMPORT=true and sign in manually the first time instead.

Login says it failed but the browser showed my inbox. Run outlook_login again and let the window close on its own. If it persists, run with MSOUTLOOK_DEBUG=true and check the stderr logs.

It opens the wrong browser. Set MSOUTLOOK_BROWSER=chrome or MSOUTLOOK_BROWSER=msedge to force one. Only Chromium based browsers (Chrome, Edge) are supported; Safari and Firefox fall back to Chrome/Edge.

Tokens stopped working after a long break. Refresh tokens last around 90 days. Run outlook_login to reauthenticate.

MIT. See LICENSE.