Overview
MailDev is a local SMTP server and web inbox for developers. Catch every email your app sends, read it in a browser or from an AI agent, and never risk sending test mail to a real person.
MailDev sits between your application and the outside world during development. Your app sends mail over SMTP exactly as it would in production; MailDev catches it, and nothing leaves your machine.
Two ports do all the work:
| Port | What listens there |
|---|---|
1025 |
The SMTP server your application sends to |
1080 |
The web inbox, the REST API, and the MCP server |
Start here #
- Install — npx, npm, or Docker.
- Quick start — point your framework at MailDev and send your first message.
- The web inbox — what you get in the UI.
Guides #
- Docker & Compose — run MailDev as a container or a Compose service.
- HTTPS — serve the web inbox over TLS.
- Testing email in CI — assert on delivered mail from your test suite.
Integrations #
Any language that speaks SMTP works without a plugin — send to localhost:1025
with authentication and TLS turned off. There are copy-paste configs for
Nodemailer,
Django,
Ruby on Rails, and
Laravel.
Reference #
- CLI & configuration — every flag, environment variable, and config-file key.
- REST API — read, search, and delete mail over HTTP.
- Programmatic API — embed MailDev in a Node.js process.
AI agents #
MailDev 3.0 ships an MCP server, so a coding agent can read the inbox you are already looking at — pull a verification link out of a signup email, confirm a password reset arrived, check what a template actually rendered.
- MCP server — enable it and connect any MCP client.
- Claude Code walkthrough — a full development loop with an agent driving MailDev.
MailDev is a development tool. It accepts mail from anyone, stores it unencrypted, and has no authentication by default. Never expose it to the public internet, and never point production traffic at it.