M365 Attachment Reader MCP

A remote MCP server for Claude that reads Outlook emails and deeply parses email attachments through the Microsoft Graph API.

Supported attachment handling now includes PDF, scanned PDF with OCR, Word, PowerPoint, Excel, CSV, plain text, images, archives, and Outlook .msg files.

Status: Early Windows-based testing version. Functional for personal use and private workflows, but not yet a production multi-user service.

Why This Exists

Claude's built-in Microsoft 365 connector can list emails, read message bodies, and check calendars. But it cannot read the actual content inside email attachments.

That means when you say "What does the PDF in my latest email say?", Claude can see the attachment metadata, but not the text, tables, images, or nested documents inside it.

This project fills that gap.

What It Does

This server sits between Claude and Microsoft 365 as a remote HTTP MCP endpoint. It:

1. Authenticates with Microsoft 365 via device code flow

2. Lists Outlook emails and their attachments through Microsoft Graph

3. Downloads attachments on the backend

4. Parses file contents and returns structured text and image blocks directly to Claude

Supported Formats

The image handling is a key differentiator: the server can return standalone image attachments as MCP image blocks, extract embedded images from DOCX and PPTX files, and fall back to OCR for scanned PDFs when no text layer exists.

MCP Tools

These short tool names are aliases for the underlying m365_* tools registered by the server.

Real-World Use Cases

Retail / Sales Operations

"Pull the last 5 Daily Dashboard emails, read the Excel attachments, and analyze the sales trend across all store locations over the past week."

Finance / Accounting

"Find the latest email from our vendor with 'Invoice' in the subject, read the PDF attachment, and extract the total amount, due date, and line items."

Legal / Contract Review

"Open the most recent email from legal@partner.com, read the Word or PowerPoint attachment, and summarize the key terms."

Executive Reporting

"Read the weekly board report attachment from the latest CFO email and summarize the charts and key metrics."

HR / Recruiting

"Find emails from recruiting@company.com with attachments, read each resume PDF, and create a comparison table of candidates."

Supply Chain / Procurement

"Read the latest supplier quote archive, extract the spreadsheets inside it, and compare unit prices against the previous quote."

Architecture

Claude Chat -> Cloudflare Tunnel -> Local Express Server -> Microsoft Graph API
                (public URL)       (localhost:8080)      (Outlook data)
                                           |
                                    Parse attachments
                              (pdf-parse, tesseract.js,
                               mammoth, xlsx, adm-zip,
                                msgreader, archive tools)

For local testing, Cloudflare Quick Tunnel exposes the local server to the internet. Claude connects via a Custom Connector pointed at the tunnel URL.

Prerequisites

• Windows 10/11 with PowerShell

• Node.js

• A Microsoft 365 / Outlook account

• A Claude account with Custom Connector support

Setup

1. Create a Microsoft Entra App Registration

Go to Microsoft Entra admin center -> App registrations -> New registration.

• Name: m365-mcp-remote

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

Then:

1. Copy the Application (client) ID and Directory (tenant) ID from the Overview page

2. Go to Authentication -> Enable Allow public client flows -> Save

3. Go to API permissions -> Add a permission -> Microsoft Graph -> Delegated permissions -> Add User.Read and Mail.Read -> Grant admin consent

2. Clone and Install

git clone https://github.com/Zacccck/MCP.git
cd MCP
npm install

3. Configure Environment

cp .env.example .env

Edit .env and fill in your Application client ID:

M365_CLIENT_ID=your-application-client-id-here
M365_TENANT_ID=common

4. Start the Server

npm start

You should see:

Custom M365 HTTP MCP server listening at http://127.0.0.1:8080/mcp

5. Expose via Cloudflare Tunnel

In a new PowerShell window:

winget install --id Cloudflare.cloudflared

Then run:

cloudflared tunnel --url http://127.0.0.1:8080

Copy the generated https://xxxxx.trycloudflare.com URL.

6. Add to Claude as a Custom Connector

In Claude Chat:

1. Click the + button near the input area

2. Open Connectors -> Add connector -> Custom Connector

3. Enter URL: https://xxxxx.trycloudflare.com/mcp

Use https:// and include /mcp at the end. Do not use http://127.0.0.1:8080/mcp.

7. Authenticate

In Claude, say:

Please call begin_auth

Claude will return a login URL and a device code. Open the URL, enter the code, and complete the Microsoft login. Then verify with:

Please call auth_status

8. Use It

Show me my recent outlook emails with attachments

Summarize the contents of the attachments from the email

Important Limitations

• Single-user: Auth state is stored in memory. One server instance equals one Microsoft account.

• Two processes required: Both node server.mjs and cloudflared tunnel must stay running during use.

• Quick Tunnel is for testing only: The Cloudflare URL changes every time you restart cloudflared.

• Manual setup required: Azure app registration, .env configuration, and connector setup are still manual.

Troubleshooting

Project Structure

MCP/
|-- server.mjs
|-- package.json
|-- .env.example
|-- .gitignore
|-- LICENSE
`-- README.md

Roadmap

• Easier first-time setup

• Account logout and switching without restart

• Windows background service mode

• Production deployment guide

• Multi-user session architecture

• Deeper OCR language coverage and better large-file summarization

Security Notes

This is a local testing and prototype implementation. It is not production-ready for public deployment. Before deploying publicly, you would need authentication in front of /mcp, per-user session isolation, secure token storage, rate limiting, and proper infrastructure.