devsmtp

DevSmtp

A lightweight SMTP server for developers to test email functionality in their applications. DevSmtp captures all emails sent to it and stores them in a SQLite database, providing a terminal-based UI for viewing and managing messages.

Features

• Full SMTP Support - Implements all standard SMTP commands (HELO, EHLO, MAIL FROM, RCPT TO, DATA, RSET, NOOP, QUIT, VRFY, EXPN)
• STARTTLS Support - Optional TLS encryption via STARTTLS
• Configurable Authentication - SMTP AUTH support with configurable credentials (optional or required)
• SQLite Storage - All messages stored locally in a SQLite database
• Terminal UI - Built-in TUI for browsing and inspecting captured emails
• Flexible Configuration - Configure via CLI flags, environment variables, or config file

Installation

From Source

git clone https://github.com/lawnchairsociety/devsmtp.git
cd devsmtp
go build -o devsmtp ./cmd/devsmtp

Go Install

go install github.com/lawnchairsociety/devsmtp/cmd/devsmtp@latest

Usage

# Start with default settings (port 587)
devsmtp

# Start on a custom port
devsmtp --port 2525

# Start with authentication required
devsmtp --auth-required --auth-user testuser --auth-pass testpass

This launches both the SMTP server and the terminal UI. The TUI displays incoming emails in real-time.

Configuration

DevSmtp can be configured through CLI flags, environment variables, or a configuration file. Priority order: CLI flags > environment variables > config file > defaults.

CLI Flags

Environment Variables

Config File

Create a devsmtp.yaml file:

server:
  host: "0.0.0.0"
  port: 587

database:
  path: "./devsmtp.db"

auth:
  required: false
  username: ""
  password: ""

tls:
  cert: ""
  key: ""

SMTP Commands

DevSmtp implements the following SMTP commands per RFC 5321:

TUI Features

The terminal UI provides:

• List view of all captured emails
• Search and filter by sender, recipient, subject
• View full email headers and body
• Delete individual or all messages
• Real-time updates as new emails arrive

Database Schema

Messages are stored in SQLite with the following schema:

CREATE TABLE messages (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    sender TEXT NOT NULL,
    recipients TEXT NOT NULL,
    subject TEXT,
    body TEXT,
    raw_data BLOB,
    size INTEGER NOT NULL DEFAULT 0,
    client_ip TEXT,
    is_read BOOLEAN NOT NULL DEFAULT 0,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX idx_messages_created_at ON messages(created_at);
CREATE INDEX idx_messages_is_read ON messages(is_read);

Development

Prerequisites

• Go 1.21 or later

Building

go build -o devsmtp ./cmd/devsmtp

Running Tests

go test ./...

License

MIT License - see LICENSE for details.