nullmail

A development SMTP server that captures emails without actually sending them, with a modern web interface for viewing received messages.

Features

• SMTP Server: Accepts emails on port 2525 (or configurable port)
• Web Interface: Modern Next.js client for viewing captured emails
• Redis Storage: Persistent email storage using Redis
• TLS Support: Supports encrypted connections
• Development Ready: Easy setup for local development and testing

Quick Start

Prerequisites

• Go 1.21.3 or higher
• Node.js and pnpm
• Docker and Docker Compose (for Redis)

Setup

1. Start Redis services:

   make docker-up

2. Run the SMTP server:

   make run

3. Start the web client (in another terminal):

   make run-client

4. Access the web interface at http://localhost:3000

Testing Email Reception

Send a test email to the SMTP server:

make test-smtp

Or manually with swaks:

swaks --to [email protected] --from [email protected] --server localhost:2525 --body "Test email"

Development

Available Commands

Go/SMTP Server:

• make run - Start SMTP server in development mode
• make build - Build the binary
• make test - Run tests
• make fmt - Format Go code
• make vet - Run go vet
• make check - Run formatting and vetting

Client:

• make run-client - Start Next.js development server

Docker:

• make docker-up - Start all services (Redis, etc.)
• make docker-down - Stop all services
• make docker-build - Build Docker image

Redis:

• make redis-logs - View Redis logs
• make redis-reset - Clear all stored emails

Project Structure

nullmail/
├── cmd/nullmail/          # Main application entry point
├── internal/              # Internal Go packages
│   ├── smtp/             # SMTP server implementation
│   ├── email/            # Email parsing and validation
│   └── redis/            # Redis client
├── client/               # Next.js web interface
│   ├── app/              # Next.js app router
│   ├── components/       # React components
│   └── lib/              # Client utilities
└── infra/                # Infrastructure configs

Configuration

Environment Variables

SMTP Server:

• DEBUG=true - Enable debug logging
• ENV=production - Set production mode
• REDIS_URL - Redis connection string (default: localhost:6379)
• REDIS_PASSWORD - Redis password (default: dev123)

Client:

• Standard Next.js environment variables

Ports

• SMTP Server: 2525 (configurable via command line argument)
• Web Client: 3000 (Next.js default)
• Redis: 6379

API

The web client connects to the SMTP server's stored emails via:

• GET /api/emails/[address] - Retrieve emails for a specific address

License

This project is for development and testing purposes.