Mailpit

Open Source

SMTP testing tool for developers with modern web UI and API

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9,374 Stars MIT v1.29.7 May 12, 2026 Since Jul 2022 5 open issues

AI Summary

Mailpit is a lightweight email testing tool that acts as an SMTP server and displays received test emails in a modern web interface. It offers a REST API for automated testing, HTML compatibility checking, spam testing and requires no additional dependencies.

✓ Pros

+ No dependencies, runs as a single binary or Docker container with minimal resource consumption
+ Extensive features like HTML checker, spam testing, screenshots and POP3 server
+ REST API enables full automation and integration into CI/CD pipelines

✗ Cons

− Only suitable for test and development environments, not for production emails
− Advanced features like spam testing require external tools such as SpamAssassin

Use Cases

→ Testing email functionality in local development environments without actual email delivery
→ Automated integration tests for email workflows via the REST API
→ Checking HTML/CSS compatibility of emails with common email clients
→ Spam testing and link validation of marketing and transactional emails

Who is it for?

Developers and QA teams who want to test email functionality locally and integrate automated email tests into their CI/CD pipelines.