SMTP MCP Server (Java SDK 0.11.0)

A comprehensive Model Context Protocol (MCP) server that provides robust email sending capabilities via SMTP integration. This server supports multiple transport protocols (STDIO, SSE, and Streamable HTTP) and exposes email functionality through both MCP tools and REST endpoints, making it ideal for integrating email capabilities into AI applications, automation workflows, and testing environments.

📋 Table of Contents

• Features
• Prerequisites
• Architecture Overview
• Installation & Building
• Configuration
• Usage
  • STDIO Transport
  • SSE Transport
  • Streamable HTTP
• Testing
• API Reference
• Related Projects
• Troubleshooting
• Performance & Monitoring
• Contributing

🚀 Features

Core Functionality

• Multiple Transport Protocols: STDIO, Server-Sent Events (SSE), and Streamable HTTP
• MCP Tool Integration: Provides a send-email tool for MCP clients
• REST API: Simple REST endpoints for testing and integration
• Gmail SMTP Support: Pre-configured for Gmail SMTP with TLS security
• Multiple Recipients: Support for TO, CC, and BCC recipients
• Health Monitoring: Built-in health check endpoints
• Claude Desktop Compatible: Ready-to-use with Claude Desktop and other MCP clients

Advanced Features

• Rich Email Formatting: Support for HTML and plain text emails
• Attachment Support (planned): File attachment capabilities
• Email Templates (planned): Reusable email templates
• Retry Mechanism: Automatic retry on failed email deliveries
• Rate Limiting: Built-in protection against spam and overuse
• Comprehensive Logging: Detailed logs for debugging and monitoring

📋 Prerequisites

• Java 21 or higher
• Maven 3.6+
• Gmail account with app-specific password (or other SMTP server credentials)
• MCP Client (Claude Desktop, custom clients, or MCP Inspector for testing)

🏗️ Architecture Overview

┌─────────────────┐    ┌──────────────────┐    ┌─────────────────┐
│   MCP Client    │    │   MCP Server     │    │   SMTP Server   │
│  (Claude, etc.) │◄───┤  (This Project)  │────►│   (Gmail, etc.) │
└─────────────────┘    └──────────────────┘    └─────────────────┘
                              │
                         ┌────▼────┐
                         │ REST API│
                         │ Testing │
                         └─────────┘

The application consists of:

• MCP Server: Handles MCP protocol communication via multiple transports
• Email Service: Core SMTP email sending functionality with JavaMail
• REST Endpoints: Additional HTTP endpoints for testing and health checks
• Transport Layer: Supports STDIO, SSE, and Streamable HTTP protocols
• Configuration Layer: Flexible configuration for different SMTP providers

🛠️ Installation & Building

1. Clone the Repository

git clone https://github.com/RayenMalouche/Java-MCP-Server-For-SMTP-Mailing.git
cd Java-MCP-Server-For-SMTP-Mailing

2. Configure Email Settings

Edit the SMTP configuration in Application.java:

// SMTP Configuration - Update these values
private static final String SMTP_USERNAME = "your-email@gmail.com";
private static final String SMTP_PASSWORD = "your-app-password";
private static final String SMTP_HOST = "smtp.gmail.com";
private static final int SMTP_PORT = 587;
private static final boolean SMTP_TLS_ENABLED = true;
private static final boolean SMTP_SSL_ENABLED = false;

3. Build the Project

# Clean build
mvn clean compile

# Create JAR file
mvn clean package -DskipTests

# Build with tests (optional)
mvn 

... [View full README on GitHub](https://github.com/RayenMalouche/Java-MCP-Server-For-SMTP-Mailing#readme)