Mailpit

Mailpit is an open-source email and SMTP testing tool that captures outbound mail from your application, displays it in a modern web UI, and exposes a REST API for automated integration tests. We rate it 92/100 — if you ever used MailHog, Mailpit is the upgrade you have been waiting for, and it is the right default for any team building transactional email today.

What is Mailpit?

Mailpit was created in July 2022 by Ralph Slooten (axllent on GitHub), the same developer behind the long-running MailHog community fork. Mailpit was written from scratch in Go with a Vue frontend and ships as a single 10–11 MB static binary or multi-arch Docker image with zero external dependencies. As of April 2026 it has 9,250+ stars on GitHub, 280+ forks, and just shipped v1.29.7 on April 16, 2026.

The pitch is direct: spin up Mailpit on your dev machine or in CI, point your app's SMTP settings at localhost:1025, and every email your code tries to send is captured into a searchable web inbox at localhost:8025. No mail leaves your machine, no risk of accidentally emailing real users from staging, and your engineers get instant feedback on rendered HTML, attachments, headers, and link integrity.

Key Features of Mailpit

• Single binary, zero dependencies: One ~11 MB static binary on Linux, macOS (amd64 + arm64), Windows, and ARM. The official Docker image is multi-arch and under 30 MB.
• Modern web UI with live updates: Built with Vue, the inbox auto-refreshes via WebSockets, supports a favicon unread counter, browser notifications, dark mode, and full-text search.
• Comprehensive REST API: A documented HTTP API to list, search, read, mark, and delete messages — the foundation for end-to-end tests in Cypress, Playwright, Pytest, or any CI runner.
• HTML compatibility & link checks: Test how your email renders against common clients (Outlook, Gmail, Apple Mail) and validate every link and tracked image without leaving the UI.
• SpamAssassin integration: Optional spam scoring on every captured message so you can catch high-spam-score templates before they ship.
• POP3 server, SMTP relay, webhooks & chaos mode: Pull captured mail into your real client over POP3, optionally relay or forward selected messages to real recipients, fire webhooks on receipt, or use Chaos mode to inject configurable SMTP errors and harden your retry logic.

What Users Say About Mailpit

Sentiment in r/selfhosted, r/golang, and r/PHP is overwhelmingly positive. The recurring theme on Hacker News and Reddit is the same one-liner: “finally, a MailHog replacement that is actually maintained.” Laravel developers in particular have adopted Mailpit en masse — it is the default mail tool shipped with Laravel Herd and the recommended local mail server in the official Laravel Sail repository.

Honest complaints are minor: a handful of users have asked for a hosted multi-tenant version (which Mailpit does not offer — that space is owned by sponsor Mailtrap), and a few have requested first-class IMAP support (the project ships POP3 but not IMAP today). On GitHub the issue tracker has only 1 open issue at time of writing — a remarkable signal of a maintainer who actually closes things.

Mailpit Pricing

Mailpit is 100% free and MIT-licensed. There is no paid tier, no telemetry, and no signup. Donations are welcome via GitHub Sponsors, and commercial sponsorship from Mailtrap helps fund continued development.

Plan	Price	Includes
Self-hosted (binary)	$0	All features, unlimited messages, no telemetry
Docker image	$0	Multi-arch, ~30 MB, ideal for docker-compose & CI
GitHub Sponsors (optional)	From $1/mo	Support the maintainer — no paywalled features

Who Should Use Mailpit?

Best for: Backend developers, full-stack teams, QA engineers, and anyone running a Laravel, Rails, Django, Node.js, or .NET app that sends transactional email. It is essentially mandatory if you run end-to-end tests that need to assert on email content.

Not ideal for: Teams that need a hosted, multi-user shared inbox with role-based access controls, fake inbox URLs for QA at scale, or built-in IMAP — Mailtrap and Ethereal remain better choices for those use cases.

Pros and Cons

Pros:

• Single static binary, no Java/Node runtime needed (a real pain point that killed MailHog adoption in slim CI containers)
• Actively maintained — v1.29.7 shipped on April 16, 2026, with 1 open issue total
• HTML compatibility check, link check, and SpamAssassin integration are unique among open-source SMTP testers
• REST API is well documented and stable enough to build CI tests against
• Default mail tool in Laravel Herd — massive battle-testing in the wild

Cons:

• No IMAP server — only POP3 (rarely a blocker, but worth knowing)
• Not designed as a hosted multi-tenant inbox — you run one instance per dev or per CI job
• Single-maintainer project — the bus factor is real, even though the codebase is small and forkable

Alternatives to Mailpit

MailHog is the spiritual predecessor — same UX, but unmaintained since 2020 and with known bugs. Mailtrap is a hosted SaaS with shared team inboxes, roles, and a generous free tier; pick it if you want a multi-user staging inbox you can share. MailDev is the Node.js equivalent — fine if you already require Node in your stack, but heavier and slower than Mailpit's Go binary.

Verdict: Is Mailpit Worth It?

Yes — unconditionally. Mailpit is the rare open-source tool with no realistic downside: it is free, MIT-licensed, actively maintained, ships a single binary, has a clean REST API, and solves a problem every team with transactional email runs into. The 92/100 rating reflects that it is essentially best-in-class for local email testing — the few points off acknowledge the missing IMAP server and the absence of a hosted multi-user mode for those who need it.

Frequently Asked Questions

Is Mailpit free?

Yes. Mailpit is fully open source under the MIT license and free to use commercially. There are no paid tiers and no telemetry.

What platforms does Mailpit support?

Mailpit ships pre-built binaries for Linux (amd64, arm64, arm, 386), macOS (amd64 + Apple Silicon), and Windows (amd64 + arm64). It also ships a multi-arch Docker image at axllent/mailpit.

How does Mailpit compare to MailHog?

Mailpit is built by the maintainer of the most-used MailHog fork. It uses the same SMTP-capture model but adds a modern Vue UI, REST API, HTML check, link check, SpamAssassin support, POP3 server, webhooks, and chaos mode — all in a single Go binary. MailHog has been unmaintained since 2020.

Is Mailpit open source?

Yes. Source is on GitHub at axllent/mailpit under the MIT license.

Can I use Mailpit in CI?

Yes — that is one of its primary use cases. Spin up the Docker image as a service container in GitHub Actions, GitLab CI, or CircleCI, send test emails to it from your app, and assert on them via the REST API.