Mailpit: The Modern Email Testing Tool Every Developer Needs

A lightweight, high-performance replacement for MailHog — built for today’s development environments

Mailpit is rapidly emerging as the go-to solution for developers who need a fast, reliable way to capture and inspect outgoing emails in development or CI/CD environments. Designed as a modern replacement for the now-unmaintained MailHog, Mailpit offers a sleek web UI, powerful features, and zero external dependencies.

Written in Go and distributed as a static binary, Mailpit acts as a full-featured SMTP server with an advanced web interface for viewing emails in real time — supporting HTML, text, headers, raw source, attachments, and mobile previews. It also includes a REST API for integration testing and an optional POP3 server for retrieving emails via standard mail clients.

Key Features

• Modern web UI with powerful search, real-time updates, and browser notifications.
• Full SMTP server with optional STARTTLS/SSL and authentication support.
• Advanced email viewer: render HTML, inspect headers, source, and attachments.
• Email quality tools: HTML compatibility checks, link validation, and spam scoring (via SpamAssassin).
• SMTP relay and forwarding to simulate real-world delivery workflows.
• High throughput, processing up to 100–200 emails per second, handling tens of thousands efficiently.
• Chaos mode to simulate SMTP errors for resilience testing.
• Email tagging and filtering, including support for plus addressing.
• Optional webhook support for integrating with custom workflows.

Additionally, developers can create HTML email screenshots, toggle mobile/tablet previews, and verify unsubscribe headers — making Mailpit especially useful for SaaS platforms, notification systems, and email campaigns under test.

Installation & Usage

Mailpit is cross-platform and easy to install:

• macOS:
  brew install mailpit
  Start as a service with:
  brew services start mailpit
• Linux/macOS sudo sh < <(curl -sL https://raw.githubusercontent.com/axllent/mailpit/develop/install.sh)
• Docker images available for 386, amd64, and arm64.
• Static binaries available for Windows, Linux, and macOS from the Releases.

By default, the web interface is accessible at http://localhost:8025 and the SMTP server listens on port 1025. Applications like PHP using sendmail can be configured to route emails through Mailpit’s SMTP server.

A Worthy Successor to MailHog

While MailHog has been widely used for years, it has lacked active development and security updates. Mailpit steps in not just as a replacement but as a complete evolution — offering more features, modern UI, better performance, and ongoing maintenance.

For modern development workflows, especially those incorporating CI pipelines, Docker, and microservices, Mailpit is a must-have tool to streamline email testing, validation, and debugging — without external dependencies or cloud reliance.

🔗 Learn more and get started on the official Mailpit GitHub repository