Mail Cal Drive

License: MIT Node.js Docker MCP

A self-hosted Model Context Protocol (MCP) server for multi-account email, calendar, and cloud storage. Connect Microsoft 365, Google Workspace, and IMAP accounts to any MCP client — Claude Desktop, Claude Code, VS Code, Cursor, and more.

Runs locally in Docker with Postgres. Credentials encrypted at rest. Survives reboots without re-authorization.

Provider	Email	Calendar	Drive
Microsoft 365	✅	✅	✅ OneDrive
Google Workspace	✅	✅	✅ Google Drive
IMAP	✅	❌	❌

Prerequisites

• Docker and Docker Compose
• Node.js 20+ (for local development only)

Quick Start

# 1. Clone
git clone https://github.com/rumbitopi/mail-cal-drive-mcp.git
cd mail-cal-drive-mcp

# 2. Configure
cp .env.example .env

# 3. Generate keys (run 3 times — one for each)
node -e "console.log(require('crypto').randomBytes(32).toString('hex'))"
# Paste into .env as POSTGRES_PASSWORD, CREDENTIAL_ENCRYPTION_KEY, and API_KEY
# Update DATABASE_URL to use the same POSTGRES_PASSWORD

# 4. Start (server runs with zero providers — configure them later)
docker compose up --build -d

# 5. Verify health
curl http://localhost:3100/health

# 6. Verify MCP
curl -X POST http://localhost:3100/mcp \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0.0"}},"id":1}'

Architecture

┌──────────────────────────────────────────────┐
│  Docker Compose                              │
│  ┌─────────────┐    ┌──────────────┐         │
│  │ workspace   │◄──►│ postgres:5432│         │
│  │ -mcp :3100  │    │ (persistent) │         │
│  │ Streamable  │    └──────────────┘         │
│  │ HTTP + Auth │                             │
│  └─────────────┘                             │
└──────────────────────────────────────────────┘

Protocol: MCP over Streamable HTTP (2024-11-05), MCP SDK 1.25.3

What persists across reboots (in Postgres):

• Credentials (AES-256-GCM encrypted)
• MSAL token cache (silent Microsoft refresh — no re-auth)
• Pending auth flows (survive restarts mid-auth)

What's ephemeral (in memory):

• MCP sessions (clients auto-reconnect)

---

Client Configuration

Claude Desktop

Claude Desktop speaks stdio, not HTTP. supergateway bridges the two.

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "workspace": {
      "command": "npx",
      "args": [
        "-y", "supergateway",
        "--streamableHttp", "http://localhost:3100/mcp",
        "--header", "Authorization: Bearer YOUR_API_KEY"
      ]
    }
  }
}

Claude Code

Add to .claude/settings.local.json in your project:

{
  "mcpServers": {
    "workspace": {
      "type": "streamable-http",
      "url": "http://localhost:3100/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_API_KEY"
      }
    }
  }
}

VS Code (GitHub Copilot)

Add to .vscode/settings.json:

{
  "github.copilot.chat.mcpServers": {
    "workspace": {
      "type": "streamable-http",
      "url": "http://localhost:3100/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_API_KEY"
      }
    }
  }
}

Cursor

Add to .cursor/mcp.json:

{
  "mcpServers": {
    "workspace": {
      "url": "http://localhost:3100/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_API_KEY"
      }
    }
  }
}

---

Provider Setup

Microsoft 365

Uses device code flow — no redirect URI needed.

Azure App Registration

1. Go to Azure Portal → Azure Active Directory → App registrations → New registration
2. Name: Workspace MCP (or anything)
3. Supported account types: "Accounts in any organizational directory and personal Microsoft accounts"
4. Redirect URI: Leave blank
5. Click Register

Enable Public Client Flow

1. Go to your app → Authentication
2. Under Advanced settings, set "Allow public client flows" to Yes
3. Click Save

Add API Permissions

1. Go to API permissions → Add a permission → Microsoft Graph → Delegated permissions
2. Add:
   • Mail.ReadWrite, Mail.Send
   • Calendars.ReadWrite, Calendars.Read.Shared
   • Files.ReadWrite, Files.ReadWrite.All
   • User.Read, offline_access
3. Click "Grant admin consent" if you're an admin

Configure .env

MS_ENABLED=true
MS_CLIENT_ID=<Application (client) ID from Overview page>
MS_TENANT_ID=<Directory (tenant) ID, or "common" for multi-tenant>

Connect

Call auth_start with provider: "microsoft". You'll get a URL and code. Visit the URL, enter the code, sign in. Then call auth_complete. One-time setup — refresh tokens persist across reboots.

---

Google Workspace

Uses OAuth callback flow — requires a redirect URI.

Google Cloud Setup

1. Go to Google Cloud Console → create or select a project
2. Enable APIs: Gmail API, Google Calendar API, Google Drive API
3. OAuth consent screen:
   • User Type: External (or Internal for Workspace)
   • Add scopes: gmail.modify, gmail.labels, calendar, calendar.events, drive, drive.file
   • Add yourself as a test user
4. Credentials → Create OAuth client ID:
   • Type: Web application
   • Redirect URI: http://localhost:3100/auth/google/callback

Configure .env

GOOGLE_ENABLED=true
GOOGLE_CLIENT_ID=<Client ID>
GOOGLE_CLIENT_SECRET=<Client Secret>
GOOGLE_REDIRECT_URI=http://localhost:3100/auth/google/callback

Connect

Call auth_start with provider: "google". Open the URL, sign in, grant permissions. The callback saves your tokens. Then call auth_complete. One-time setup.

---

IMAP

No external setup needed — provide credentials directly.

Connect

Call auth_start with:

provider: "imap"
accountName: "Personal Email"
email: "[email protected]"
imapHost: "imap.example.com"
imapPort: 993
imapUsername: "[email protected]"
imapPassword: "your-app-password"
imapTls: true

No auth_complete needed — IMAP accounts are ready immediately.

Common IMAP Servers

Provider	Host	Port	Notes
Gmail	imap.gmail.com	993	Requires App Password
Outlook/Hotmail	outlook.office365.com	993	Requires App Password
Yahoo	imap.mail.yahoo.com	993	Requires App Password
Fastmail	imap.fastmail.com	993	Requires App Password

---

MCP Tools (36 total)

Authentication (4)

Tool	Description
auth_status	List all accounts with connection status
auth_start	Start OAuth/device code flow or IMAP setup
auth_complete	Complete pending authentication
auth_revoke	Remove an account

Email (10)

Tool	Description
list_accounts	List all configured email accounts
list_folders	Get folders/labels for an account
list_messages	Messages with pagination
get_message	Full message with body and attachments
get_attachment	Download attachment (text decoded, binary as blob)
search_messages	Search with filters (see parameters below)
move_message	Move to folder
delete_message	Trash or permanent delete
mark_read	Mark read/unread
bulk_mail_action	Batch operations with dry-run support

Calendar (8)

Tool	Description
list_calendars	All calendars for an account
list_events	Events in a date range
get_event	Full event details
create_event	Create with attendees, recurrence, conferencing
update_event	Modify existing event
delete_event	Delete event
find_free_time	Find available time slots across accounts
check_conflicts	Detect scheduling conflicts

Drive (14)

Tool	Description
list_files	List files and folders
get_file	File metadata
get_file_content	Download file content
search_files	Search by name, content, or type
upload_file	Upload new file (text or base64)
create_folder	Create folder
move_file	Move file/folder
copy_file	Copy file
rename_file	Rename file/folder
delete_file	Delete (trash or permanent)
get_sharing	View sharing permissions
share_file	Share with user or create link
unshare_file	Remove sharing
get_storage_quota	Storage usage info

---

Tool Parameter Reference

get_attachment

Parameter	Type	Required	Description
accountId	string	Yes	Account ID
messageId	string	Yes	Message ID
attachmentId	string	Yes	Attachment ID from get_message

Returns text content for text-based files, or an MCP EmbeddedResource with blob for binary files (PDF, images, etc.). Max 5MB.

search_messages

Parameter	Type	Required	Description
accountIds	string[]	Yes	Account IDs to search
from	string	No	Filter by sender email
to	string	No	Filter by recipient email
subject	string	No	Filter by subject (partial match)
body	string	No	Search in message body
folder	string	No	Limit to specific folder
hasAttachment	boolean	No	Filter by attachment presence
isRead	boolean	No	Filter by read status
isStarred	boolean	No	Filter by starred status
after	string	No	Messages after date (ISO 8601)
before	string	No	Messages before date (ISO 8601)
labels	string[]	No	Filter by labels (Gmail)
limit	number	No	Max results per account (default: 50)

create_event

Parameter	Type	Required	Description
accountId	string	Yes	Account ID
title	string	Yes	Event title
startTime	string	Yes	Start time (ISO 8601)
endTime	string	Yes	End time (ISO 8601)
calendarId	string	No	Calendar ID (default: primary)
description	string	No	Event description
location	string	No	Event location
isAllDay	boolean	No	All-day event
timeZone	string	No	Time zone (default: UTC)
attendees	array	No	[{email, optional?}]
visibility	string	No	"public" or "private"
addConference	boolean	No	Add video conference link

bulk_mail_action

Parameter	Type	Required	Description
accountId	string	Yes	Account ID
action	string	Yes	"move", "delete", "markRead", "markUnread", "star", "unstar", "archive"
dryRun	boolean	No	Preview without executing (default: false)
targetFolder	string	No	Destination folder (required for "move")
from	string	No	Filter by sender
subject	string	No	Filter by subject
folder	string	No	Limit to folder
isRead	boolean	No	Filter by read status
after	string	No	After date (ISO 8601)
before	string	No	Before date (ISO 8601)
limit	number	No	Max messages to process

find_free_time

Parameter	Type	Required	Description
accountIds	string[]	Yes	Account IDs to check
startDate	string	Yes	Start of range (ISO 8601)
endDate	string	Yes	End of range (ISO 8601)
duration	number	Yes	Required duration in minutes
calendarIds	string[]	No	Calendars to check (default: primary)

upload_file

Parameter	Type	Required	Description
accountId	string	Yes	Account ID
name	string	Yes	File name
content	string	Yes	File content (text or base64)
folderId	string	No	Parent folder ID (default: root)
mimeType	string	No	MIME type
isBase64	boolean	No	Content is base64 encoded

share_file

Parameter	Type	Required	Description
accountId	string	Yes	Account ID
fileId	string	Yes	File ID
type	string	Yes	"user", "group", or "anyone"
role	string	Yes	"reader", "writer", or "commenter"
email	string	No	Email (required for user/group)
sendNotification	boolean	No	Send email notification
message	string	No	Notification message

---

Environment Variables

Variable	Required	Default	Description
DATABASE_URL	Yes	—	Postgres connection string
POSTGRES_PASSWORD	Yes	—	Postgres password (used by Docker Compose)
CREDENTIAL_ENCRYPTION_KEY	Yes	—	64 hex chars (32 bytes) for AES-256-GCM
API_KEY	Yes	—	Min 32 chars, used as Bearer token
NODE_ENV	No	development	development or production
MCP_PORT	No	3100	Server port
LOG_LEVEL	No	info	error, warn, info, debug
MS_ENABLED	No	false	Enable Microsoft 365
MS_CLIENT_ID	If MS	—	Azure App client ID
MS_TENANT_ID	If MS	common	Azure tenant ID
GOOGLE_ENABLED	No	false	Enable Google Workspace
GOOGLE_CLIENT_ID	If Google	—	OAuth client ID
GOOGLE_CLIENT_SECRET	If Google	—	OAuth client secret
GOOGLE_REDIRECT_URI	If Google	—	OAuth callback URL
IMAP_ENABLED	No	true	Enable IMAP provider

Endpoints

Endpoint	Method	Auth	Description
/health	GET	No	Health check
/mcp	POST	Bearer	MCP JSON-RPC endpoint
/mcp	GET	Bearer	SSE stream for notifications
/mcp	DELETE	Bearer	Session cleanup
/auth/google/callback	GET	No	Google OAuth redirect handler

Security

This server is designed for localhost use only. Do not expose it to the internet without additional hardening.

• Encryption at rest: All credentials, MSAL token cache, and pending auth flows encrypted with AES-256-GCM before storage in Postgres
• Bearer auth: Timing-safe token comparison (crypto.timingSafeEqual) on all protected endpoints
• Session limits: Max 100 concurrent sessions, 30-minute TTL with automatic eviction
• Network: Binds to 127.0.0.1 only — not accessible from other machines
• Body size: 10MB request limit to prevent memory exhaustion
• IMAP note: IMAP credentials are passwords (not OAuth tokens) — encrypted at rest, but inherently less secure than OAuth. Use app passwords where possible.
• Logging: All logs to stderr (MCP requirement). No tokens, passwords, or keys logged.
• Token rotation: To rotate the encryption key, generate a new one, re-run auth_start for each account, and update .env. There is no in-place re-encryption (accounts must be re-authorized).

See SECURITY.md for vulnerability reporting.

Troubleshooting

Container won't start

• Check docker compose logs workspace-mcp for errors
• Verify DATABASE_URL matches the Postgres container credentials
• Ensure Postgres is healthy: docker compose logs postgres

Microsoft device code expired

• Device codes expire after 15 minutes. Call auth_start again for a fresh code.

Google OAuth: "Access blocked" or consent screen issues

• Make sure your Google Cloud app is in "Testing" mode with your email added as a test user
• Verify the redirect URI in Google Cloud Console matches GOOGLE_REDIRECT_URI exactly

IMAP connection refused

• Verify host, port, and TLS settings for your provider
• Most providers require an App Password when 2FA is enabled (not your regular password)
• Check if your provider blocks third-party IMAP access (Gmail: enable "Less secure apps" or use App Password)

"Invalid or expired session" on tool calls

• MCP sessions expire after 30 minutes of inactivity and are lost on container restart. Your client should auto-reconnect. If not, restart the client.

Development

# Install dependencies
npm install

# Start with hot reload (requires local Postgres on DATABASE_URL)
npm run dev

# Build TypeScript
npm run build

# Production start
npm start

# Run tests
npm test

# Type check
npm run typecheck

# Migrate credentials from old file-based storage
DATABASE_URL=... CREDENTIAL_ENCRYPTION_KEY=... npm run migrate

Project Structure

mail-cal-drive-mcp/
├── src/
│   ├── index.ts              # Entry point
│   ├── server.ts             # Express server
│   ├── config.ts             # Environment config
│   ├── logger.ts             # Structured console logger
│   ├── auth/
│   │   ├── types.ts          # Credential interfaces
│   │   ├── storage.ts        # Postgres credential storage
│   │   └── bearer.ts         # Bearer token middleware
│   ├── storage/
│   │   ├── postgres.ts       # Postgres client + encrypted CRUD
│   │   ├── msal-cache.ts     # MSAL cache plugin (Postgres)
│   │   └── pending-flows.ts  # Pending auth flow storage
│   ├── providers/
│   │   ├── base.ts           # Abstract interfaces
│   │   ├── types.ts          # Shared types
│   │   ├── microsoft/        # Graph API (mail, calendar, drive)
│   │   ├── google/           # Google APIs (Gmail, Calendar, Drive)
│   │   └── imap/             # ImapFlow (mail only)
│   ├── mcp/
│   │   ├── handler.ts        # MCP request routing
│   │   ├── session.ts        # Session management
│   │   └── tools/            # 35 MCP tools
│   └── utils/                # Timezone, recurrence, MIME helpers
├── db/migrations/            # Postgres schema
├── docker-compose.yml
├── Dockerfile
└── .env                      # Configuration (gitignored)

License

MIT