README.md•13.4 kB
# MCP Sendmail Server
A Model Context Protocol (MCP) server with **Streamable HTTP transport** for sending emails via SMTP.
## Features
- ✅ **MCP Streamable HTTP** - Full MCP specification compliance (2024-11-05)
- ✅ **Stateful Sessions** - Session management with automatic cleanup
- ✅ **Bidirectional Communication** - SSE for server-to-client messaging
- ✅ **Stream Resumability** - Reconnect and resume from last event
- ✅ **Email Tools** - Send emails, bulk emails, and template-based emails
- ✅ **SMTP Support** - Full SMTP/TLS support with authentication
- ✅ **Attachments** - Support for email attachments (base64 encoded)
- ✅ **Docker Ready** - Multi-stage build, production-optimized
- ✅ **Type Safe** - Full Python type hints and Pydantic models
- ✅ **Async Support** - FastAPI async/await patterns
- ✅ **Backward Compatible** - Legacy JSON-RPC 2.0 endpoints still work
## Configuration
SMTP credentials are configured via environment variables. The repository includes `.env.sh` for easy configuration:
```bash
# Source SMTP settings
source .env.sh
# Your settings are now available:
# SMTP_HOST, SMTP_PORT, SMTP_USER, SMTP_PASSWORD
```
## Quick Start
### Option 1: Local Development
```bash
# Create virtual environment
python -m venv venv
source venv/bin/activate # Windows: venv\Scripts\activate
# Install dependencies
pip install -r requirements.txt
# Load SMTP settings from .env.sh
source .env.sh
# Run server
uvicorn src.server:app --reload --port 8080
```
### Option 2: Docker
```bash
# Build and run with Docker
docker build -t mcp-sendmail-server:latest .
docker run -d -p 8080:8080 \
-e SMTP_HOST="smtp.gmail.com" \
-e SMTP_PORT="587" \
-e SMTP_USER="your-email@gmail.com" \
-e SMTP_PASSWORD="your-password" \
-v $(pwd)/logs:/app/logs \
--name mcp-sendmail \
mcp-sendmail-server:latest
```
### Option 3: Docker Compose (Recommended)
#### Quick Start with Convenience Scripts
```bash
# Start the server (automatically loads .env.sh)
./start.sh
# View logs
docker compose logs -f
# Stop the server
./stop.sh
```
#### Manual Start
Configure your SMTP credentials using `.env.sh`:
```bash
# 1. Edit .env.sh with your SMTP credentials (already configured in this repo)
nano .env.sh
# Example .env.sh contents:
export SMTP_HOST="mail.example.com"
export SMTP_PORT="25"
export SMTP_USER="test@example.com"
export SMTP_PASSWORD="your-password"
# 2. Source the environment variables
source .env.sh
# 3. Start services (will use variables from .env.sh)
docker compose up -d
# View logs
docker compose logs -f
# Stop services
docker compose down
```
**Important:** Always run `source .env.sh` before `docker compose up` to load the SMTP configuration, or use the `./start.sh` script which does this automatically.
**How it works:** The docker-compose.yml reads environment variables from your shell using `${SMTP_HOST}` syntax. If variables aren't set, it falls back to safe defaults (localhost:587).
## Environment Variables
| Variable | Description | Default |
|----------|-------------|---------|
| `SMTP_HOST` | SMTP server hostname | `localhost` |
| `SMTP_PORT` | SMTP server port | `587` |
| `SMTP_USER` | SMTP username/email | `` |
| `SMTP_PASSWORD` | SMTP password | `` |
## Testing the Server
### MCP Streamable HTTP (Recommended)
```bash
# Check health
curl http://localhost:8080/health
# Initialize MCP session (note the /mcp endpoint)
curl -X POST http://localhost:8080/mcp \
-H "Content-Type: application/json" \
-H "Accept: application/json" \
-d '{
"jsonrpc": "2.0",
"id": 1,
"method": "initialize",
"params": {
"protocolVersion": "2024-11-05",
"capabilities": {},
"clientInfo": {"name": "curl-client", "version": "1.0"}
}
}'
# Save the Mcp-Session-Id from response headers!
# Example: Mcp-Session-Id: 318a19a9-b757-4c0b-9ddb-a8dc1b40d240
# List available tools
curl -X POST http://localhost:8080/mcp \
-H "Content-Type: application/json" \
-H "Mcp-Session-Id: YOUR_SESSION_ID_HERE" \
-d '{
"jsonrpc": "2.0",
"id": 2,
"method": "tools/list",
"params": {}
}'
# Verify SMTP connection
curl -X POST http://localhost:8080/mcp \
-H "Content-Type: application/json" \
-H "Mcp-Session-Id: YOUR_SESSION_ID_HERE" \
-d '{
"jsonrpc": "2.0",
"id": 3,
"method": "tools/call",
"params": {
"name": "verify_connection",
"arguments": {}
}
}'
# Send an email
curl -X POST http://localhost:8080/mcp \
-H "Content-Type: application/json" \
-H "Mcp-Session-Id: YOUR_SESSION_ID_HERE" \
-d '{
"jsonrpc": "2.0",
"id": 4,
"method": "tools/call",
"params": {
"name": "send_email",
"arguments": {
"to": "recipient@example.com",
"subject": "Test Email",
"body": "This is a test email sent via MCP Sendmail Server"
}
}
}'
# Send an HTML email
curl -X POST http://localhost:8080/mcp \
-H "Content-Type: application/json" \
-H "Mcp-Session-Id: YOUR_SESSION_ID_HERE" \
-d '{
"jsonrpc": "2.0",
"id": 5,
"method": "tools/call",
"params": {
"name": "send_email",
"arguments": {
"to": "recipient@example.com",
"subject": "HTML Test Email",
"body": "<h1>Hello</h1><p>This is an <strong>HTML</strong> email!</p>",
"html": true
}
}
}'
# Send bulk emails
curl -X POST http://localhost:8080/mcp \
-H "Content-Type: application/json" \
-H "Mcp-Session-Id: YOUR_SESSION_ID_HERE" \
-d '{
"jsonrpc": "2.0",
"id": 6,
"method": "tools/call",
"params": {
"name": "send_bulk_email",
"arguments": {
"recipients": ["user1@example.com", "user2@example.com", "user3@example.com"],
"subject": "Bulk Email",
"body": "This email was sent to multiple recipients"
}
}
}'
# Send template email
curl -X POST http://localhost:8080/mcp \
-H "Content-Type: application/json" \
-H "Mcp-Session-Id: YOUR_SESSION_ID_HERE" \
-d '{
"jsonrpc": "2.0",
"id": 7,
"method": "tools/call",
"params": {
"name": "send_template_email",
"arguments": {
"to": "recipient@example.com",
"subject": "Welcome {name}!",
"template": "Hello {name},\n\nWelcome to {company}!\n\nYour account is: {account}",
"variables": {
"name": "John Doe",
"company": "Acme Corp",
"account": "john.doe@acme.com"
}
}
}
}'
```
## Available MCP Tools
### 1. `send_email`
Send an email with optional attachments, CC, and BCC.
**Parameters:**
- `to` (string, required): Recipient email address
- `subject` (string, required): Email subject
- `body` (string, required): Email body content
- `from_addr` (string, optional): Sender email address (defaults to SMTP_USER)
- `cc` (array, optional): List of CC recipients
- `bcc` (array, optional): List of BCC recipients
- `html` (boolean, optional): Whether body is HTML (default: false)
- `attachments` (array, optional): List of attachments with filename and base64 content
**Example:**
```json
{
"to": "recipient@example.com",
"subject": "Meeting Tomorrow",
"body": "Hi, let's meet tomorrow at 10 AM.",
"cc": ["manager@example.com"],
"html": false
}
```
### 2. `send_bulk_email`
Send the same email to multiple recipients.
**Parameters:**
- `recipients` (array, required): List of recipient email addresses
- `subject` (string, required): Email subject
- `body` (string, required): Email body content
- `from_addr` (string, optional): Sender email address (defaults to SMTP_USER)
- `html` (boolean, optional): Whether body is HTML (default: false)
**Example:**
```json
{
"recipients": ["user1@example.com", "user2@example.com", "user3@example.com"],
"subject": "System Maintenance Notice",
"body": "The system will be down for maintenance on Saturday."
}
```
### 3. `send_template_email`
Send an email using a template with variable substitution.
**Parameters:**
- `to` (string, required): Recipient email address
- `subject` (string, required): Email subject
- `template` (string, required): Email template with {variable} placeholders
- `variables` (object, required): Dictionary of variable names and values
- `from_addr` (string, optional): Sender email address (defaults to SMTP_USER)
- `html` (boolean, optional): Whether template is HTML (default: false)
**Example:**
```json
{
"to": "customer@example.com",
"subject": "Order Confirmation",
"template": "Dear {customer_name},\n\nYour order #{order_id} has been confirmed.\n\nTotal: ${total}",
"variables": {
"customer_name": "Jane Smith",
"order_id": "12345",
"total": "99.99"
}
}
```
### 4. `verify_connection`
Verify SMTP connection and credentials.
**Parameters:** None
**Returns:** Connection status, server details, and port information
## API Endpoints
### MCP Streamable HTTP (Primary)
| Method | Endpoint | Description |
|--------|----------|-------------|
| POST | `/mcp` | MCP requests with session management |
| GET | `/mcp` | Open SSE stream for server notifications |
| GET | `/health` | Health check |
**Required Headers:**
- `Mcp-Session-Id`: Session ID (after initialize)
- `Mcp-Protocol-Version`: `2024-11-05`
- `Accept`: `application/json, text/event-stream`
### Legacy Endpoints (Backward Compatible)
| Method | Endpoint | Description |
|--------|----------|-------------|
| POST | `/`, `/rpc`, `/jsonrpc` | Plain JSON-RPC 2.0 (no sessions) |
| GET | `/sse` | Legacy SSE (deprecated) |
### JSON-RPC Methods
| Method | Description |
|--------|-------------|
| `initialize` | Initialize MCP session (returns session ID) |
| `ping` | Keep-alive ping |
| `tools/list` | List available tools |
| `tools/call` | Execute a tool |
## Project Structure
```
mcp-mail/
├── src/
│ ├── server.py # FastAPI server with tool registration
│ ├── mcp_handler.py # MCP protocol implementation
│ ├── mcp_transport.py # MCP transport layer
│ ├── mcp_session.py # Session management
│ ├── email/
│ │ ├── __init__.py
│ │ └── email_operations.py # Email sending via SMTP
│ ├── jsonrpc/
│ │ ├── __init__.py
│ │ ├── handler.py # JSON-RPC handler
│ │ └── models.py # JSON-RPC models
│ └── utils/
│ ├── errors.py # Custom exceptions
│ ├── validation.py # Input validation
│ └── security.py # Security utilities
├── tests/ # Test suite
├── logs/ # Application logs
├── Dockerfile # Docker image definition
├── docker-compose.yml # Docker Compose setup
└── requirements.txt # Python dependencies
```
## SMTP Configuration Examples
### Gmail
```bash
export SMTP_HOST="smtp.gmail.com"
export SMTP_PORT="587"
export SMTP_USER="your-email@gmail.com"
export SMTP_PASSWORD="your-app-password" # Use App Password, not regular password
```
### Outlook/Office 365
```bash
export SMTP_HOST="smtp.office365.com"
export SMTP_PORT="587"
export SMTP_USER="your-email@outlook.com"
export SMTP_PASSWORD="your-password"
```
### SendGrid
```bash
export SMTP_HOST="smtp.sendgrid.net"
export SMTP_PORT="587"
export SMTP_USER="apikey"
export SMTP_PASSWORD="your-sendgrid-api-key"
```
### Mailgun
```bash
export SMTP_HOST="smtp.mailgun.org"
export SMTP_PORT="587"
export SMTP_USER="postmaster@your-domain.mailgun.org"
export SMTP_PASSWORD="your-mailgun-smtp-password"
```
### Amazon SES
```bash
export SMTP_HOST="email-smtp.us-east-1.amazonaws.com"
export SMTP_PORT="587"
export SMTP_USER="your-ses-smtp-username"
export SMTP_PASSWORD="your-ses-smtp-password"
```
## Security Features
- **TLS Encryption**: All SMTP connections use TLS by default
- **Secure Credentials**: SMTP credentials stored in environment variables
- **Input Validation**: Email addresses and content validated
- **Non-root User**: Docker runs as `mcpuser` (UID 1000)
## Development
```bash
# Install dev dependencies
pip install -r requirements.txt
# Run tests
pytest tests/ -v
# Type checking
mypy src/
# Linting
ruff check src/
# Code formatting
black src/
```
## Docker Image Details
- **Base Image**: `python:3.11-slim`
- **Size**: ~150-200MB (optimized with multi-stage build)
- **User**: Non-root `mcpuser`
- **Health Checks**: Built-in
- **Volumes**: `/app/logs` (logs)
## Troubleshooting
### Gmail Authentication Issues
If you're using Gmail, you need to:
1. Enable 2-factor authentication
2. Generate an App Password (not your regular password)
3. Use the App Password in `SMTP_PASSWORD`
### Connection Timeouts
If you get connection timeouts:
1. Check your firewall settings
2. Verify the SMTP host and port
3. Try port 465 (SSL) instead of 587 (TLS)
4. Use the `verify_connection` tool to test
### Certificate Errors
If you get SSL certificate errors:
1. Make sure you're using a valid SMTP server
2. Check if your network has SSL inspection enabled
3. Verify the server's certificate is valid
## License
MIT License
## Contributing
1. Fork the repository
2. Create a feature branch
3. Commit your changes
4. Push to the branch
5. Create a Pull Request
## Support
For issues and questions, please open an issue on GitHub.