Mailpit features

Mailpit is packed full of features for developers wanting to test SMTP and emails. It acts as an SMTP server, provides a modern web interface to view & test intercepted emails. It also contains an API for automated integration testing.

Some of the main features include:

  • Runs entirely from a single static binary or multi-architecture Docker images.
  • Modern web UI with advanced mail search to view emails (formatted HTML, highlighted HTML source, text, headers, raw source, and MIME attachments including image thumbnails), with optional HTTPS and authentication.
  • SMTP server with optional STARTTLS or SSL/TLS, and authentication (including an “accept any” mode).
  • A REST API for integration testing.
  • Real-time web UI updates using web sockets for new mail, with optional browser notifications when new mail is received.
  • Optional POP3 server to download captured messages directly into your email client.
  • HTML check to test and score mail client compatibility with HTML emails.
  • Link check to test message links (HTML and text) and linked images.
  • Spam check to test message “spamminess” using a running SpamAssassin server.
  • Create screenshots of HTML messages via the web UI.
  • Mobile and tablet HTML preview toggle in desktop mode.
  • Message tagging, including manual tagging or automated tagging using filtering and “plus addressing”.
  • SMTP relaying (message release) — relay messages via a different SMTP server, including an optional allowlist of accepted recipients.
  • SMTP forwarding — automatically forward messages via a different SMTP server to predefined email addresses.
  • Chaos feature to enable configurable SMTP errors for testing application resilience.
  • Fast message storing and processing — ingest 100–200 emails per second over SMTP (depending on CPU, network speed, and email size), easily handling tens of thousands of emails, with automatic email pruning (by default, keeping the most recent 500 emails).
  • List-Unsubscribe syntax validation.
  • Optional webhook for received messages.

Edit this page