Outlook MCP Server

Public Outlook / Microsoft 365 mail MCP server — Streamable HTTP + OAuth 2.1, same architecture as the Salesforce MCP Server. One deployed URL works with:

• Archon AI portal (Managed MCP via Anthropic / OpenAI)

• Claude.ai custom connectors

• ChatGPT custom MCP

• Any standalone MCP client (n8n, Cursor, custom apps) via the PATH B flow

Tools (11)

Related MCP server: Outlook Graph MCP

Setup

1. Azure app registration (one-time)

1. https://entra.microsoft.com → App registrations → New registration

2. Supported account types: Accounts in any organizational directory and personal Microsoft accounts

3. Redirect URIs (type Web):

   • https://claude.ai/api/mcp/auth_callback (Claude connector)

   • <BASE_URL>/auth/callback (PATH B standalone)

4. API permissions → Microsoft Graph → Delegated: Mail.Read, Mail.ReadWrite, Mail.Send, User.Read, offline_access

5. Certificates & secrets → New client secret → copy the Value

2. Run

cp .env.example .env      # fill in MS_CLIENT_ID / MS_CLIENT_SECRET / BASE_URL
npm install
npm run dev               # http://localhost:3100

3. Deploy (Render)

• Build command: npm install

• Start command: npm start

• Env vars: BASE_URL (the Render URL), MS_CLIENT_ID, MS_CLIENT_SECRET, MS_TENANT=common, MS_REDIRECT_URI=<BASE_URL>/auth/callback

• After deploy, add <BASE_URL>/auth/callback to the Azure app's redirect URIs.

Auth paths

PATH A — Bearer header (portals, Claude connector). The client sends Authorization: Bearer <graph access token> on /mcp. Tokens acquired through this server's /token proxy get vaulted, enabling server-side refresh when Graph returns 401 (Graph tokens live ~1 hour).

PATH B — session flow (standalone clients). Visit <BASE_URL>/auth?session=<id> → Microsoft login → tokens stored server-side keyed by the stable Microsoft user id.

The /authorize and /token proxies force the real Azure client credentials so Dynamic Client Registration (Claude invents a random client id) still works — the only requirement is the client's redirect URI being whitelisted on the Azure app.