Introduction

RustMail is a local SMTP mail catcher. Point your app's outbound email at it during development or testing, and every message lands in a web UI instead of a real inbox.

It ships as a single binary — the frontend is compiled in, so there's nothing else to install or run.

Why RustMail?

Most alternatives are either unmaintained (MailHog), minimal (MailCrab), or cloud-only (Mailtrap). RustMail is a self-hosted option that doesn't cut corners:

• Emails stick around — SQLite by default, survives restarts. Or --ephemeral for throwaway CI runs.
• Search that works — FTS5 across subject, body, sender, and recipients.
• Real-time UI — WebSocket push, dark mode, keyboard shortcuts. Feels like a proper email client.
• CI-first — REST assertion endpoints, a CLI assert mode, and a GitHub Action.
• Zero runtime deps — one binary, frontend baked in. Also ships as a ~15 MB Docker image.

How It Works

SMTP Client (your app)
    │
    ▼
rustmail-smtp  ─── tokio TCP listener, ESMTP handshake
    │
    ▼  broadcast channel
rustmail-storage  ─── sqlx + SQLite + FTS5
    │
    ▼  event broadcast
rustmail-api  ─── axum
    ├── REST endpoints  →  HTTP clients / CI pipelines
    └── WebSocket       →  Browser (SolidJS UI)

Configure your application to send mail to localhost:1025. Open http://localhost:8025 to see captured emails in real time.