Outlook-Mail-MCP

Minimalist email MCP for the home machine: connect one Outlook mailbox, read emails, and reply to emails.

🤝 Co-created by Lynn & Sage (ChatGPT)

This project was designed, implemented, and debugged together by Lynn and Sage (ChatGPT).

This project does only three things:

• 📬 View recent emails

• 📖 Read emails

• ↩️ Reply to emails

No calendar, no cloud drive, no Power Automate, and no multi-account management.

Approach

This solution uses Render Web Service + Microsoft Outlook / Microsoft Graph + OAuth 2.0 as the primary deployment method, suitable for providing mailbox capabilities as a remote MCP service to the home machine.

It can also run in any environment that supports Node.js, HTTPS, and persistent token storage, but the project's default configuration and deployment files are based on Render.

Related MCP server: outlook-mcp

Usage

After deploying to Render, open the service homepage, click Connect Outlook Mailbox, and complete Microsoft sign-in and authorization.

After authorization, connect the MCP address https://你的服务地址/mcp to your home machine.

Microsoft Configuration

Create an app in Microsoft Entra / Azure App Registration and enable the following delegated permissions:

• openid

• profile

• offline_access

• User.Read

• Mail.Read

• Mail.ReadWrite

• Mail.Send

Redirect URI:

https://你的服务地址/auth/callback

Select Web as the application type.

Environment Variables

MS_CLIENT_ID=你的 Application (client) ID
MS_CLIENT_SECRET=你的 Client Secret VALUE
MS_TENANT_ID=common
TOKEN_DIR=/data

On Render, the server prefers PUBLIC_URL; otherwise, it uses RENDER_EXTERNAL_URL automatically provided by Render to generate the OAuth callback URL.

Render Deployment

The repository already includes render.yaml and can be deployed directly using Render Blueprint.

The Render configuration includes:

• Node.js Web Service

• /health health check

• 1 GB persistent disk

• /data token storage directory

• Environment variables required by Microsoft OAuth

Tokens are stored on Render's persistent disk and will not be committed to GitHub.

MCP Tools

Local Run

npm install
npm start

Default address: http://localhost:3000/.

Local OAuth callback: http://localhost:3000/auth/callback.

Security

OAuth password is not handed over to the home machine. After Microsoft sign-in is complete, the service only saves the OAuth token; the token file permissions are set to allow read/write only by the current process user.

Credits

Lynn × Sage（ChatGPT）
A human developer + an AI partner, who built this little tool together. 🫳