RustMail

A fast, self-hosted SMTP mail catcher for development and testing.
Capture outbound email, inspect it in a modern UI, and assert on it in CI.

Documentation · API Reference · Docker Hub

Quick Start

docker run -p 1025:1025 -p 8025:8025 smyile/rustmail:latest

Point your app's SMTP at localhost:1025, then open localhost:8025. Emails appear in real time.

Docker Compose

services:
  rustmail:
    image: smyile/rustmail:latest
    ports:
      - "1025:1025"
      - "8025:8025"
    volumes:
      - rustmail-data:/data
    restart: unless-stopped

volumes:
  rustmail-data:

Install

Homebrew

brew install rustmailapp/rustmail/rustmail

Arch Linux (AUR)

yay -S rustmail-bin

From Source

git clone https://github.com/rustmailapp/rustmail
cd rustmail && make build

Pre-built Binaries

Download from GitHub Releases — Linux (x86_64, aarch64, armv7 — glibc + musl), macOS (Intel + Apple Silicon), and multi-arch Docker images.

Features

Persistent storage	SQLite-backed, emails survive restarts. --ephemeral for CI.
Full-text search	FTS5 across subject, body, sender, and recipients.
Real-time UI	WebSocket push — new email appears instantly. Dark/light mode, keyboard shortcuts.
CI-native	REST assertion endpoints, CLI assert mode, and a first-party GitHub Action.
Single binary	Frontend embedded at compile time. ~7 MB, zero runtime dependencies.
Auth header display	Parses DKIM, SPF, DMARC, and ARC headers with color-coded status badges.
Webhooks	Fire-and-forget POST on every new message.
Email release	Forward captured emails to a real SMTP server.
Export	Download any email as EML or JSON.
Retention policies	Auto-purge by age (--retention) or count (--max-messages).
TUI	Optional terminal UI client for Neovim and headless workflows.

GitHub Action

- uses: rustmailapp/rustmail-action@v1

- run: npm test  # your app sends emails to localhost:1025

- uses: rustmailapp/rustmail-action@v1
  with:
    mode: assert
    assert-count: 1
    assert-subject: "Welcome"

CLI Assert Mode

Run as an ephemeral mail catcher that exits with a status code — for CI without the GitHub Action:

rustmail assert --min-count=2 --subject="Welcome" --timeout=30s

Configuration

Configure via CLI flags, RUSTMAIL_* environment variables, or a TOML config file:

rustmail serve --bind 0.0.0.0 --smtp-port 2525 --http-port 9025
rustmail serve --retention 24 --max-messages 1000
rustmail serve --webhook-url https://hooks.example.com/email

See the full configuration reference.

TUI

A terminal UI that connects to a running RustMail instance. Also available as a Neovim plugin.

Documentation

Full docs at docs.rustmail.app:

• Getting Started
• Docker
• Configuration
• CI Integration
• API Reference

License

Licensed under either of:

• MIT License
• Apache License, Version 2.0

at your option.