Mailpit

Web · Windows · Mac · Linux · Self-hosted · API

Freedom report

Three barsScore 6.7

Free tierA free tier is on its own pricing page
Open codeNo open-source code on record
Runs widely4 of 6 device platforms
DocumentedPlans, terms and facts published

Mailpit is ranked #1 of 28 in email testing software on Freedom251. It runs on API, Linux, macOS, Self-hosted, Web, Windows. There is a free plan.

Mailpit plans and pricing

All plans

Mailpit Free Single static binary or multi-architecture Docker images · Default retention: most recent 500 emails mailpit.axllent.org · 4 Oct 2026

Compared on email testing software

Device coverage: both
Spam checks: Yes
Link checks: Yes
Inbox testing: Yes
API access: Yes

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The record

Purpose: Mailpit is an open-source utility for testing emails and SMTP delivery, with a local SMTP server, web interface, and integration-testing API.
Developer features: The web UI can show formatted HTML, HTML source, text, headers, raw source, and MIME attachments, including image thumbnails.
Email checks: Mailpit offers HTML email compatibility checks, link checks, SpamAssassin-based spam checks, and HTML message screenshots.
Message handling: Messages can be tagged, relayed through another SMTP server, automatically forwarded, or used to trigger configurable SMTP errors for resilience testing.
Automation: Mailpit provides a REST API for accessing, searching, deleting, sending, tagging, and releasing messages.
Integrations: Mailpit can send message-summary webhooks to external services, has been tested with n8n, and has a Cypress package for integration tests.
Deployment: Mailpit runs as a single binary or multi-architecture Docker image, and publishes static binaries for Windows, Linux, and Mac.
Security controls: The web UI and API can use HTTPS and basic authentication, while SMTP supports optional STARTTLS or SSL/TLS and authentication.
Email rendering security: The UI applies a strict Content-Security-Policy that blocks remote content other than images, stylesheets, and fonts, and sets a no-referrer policy.
Default SMTP configuration: By default, SMTP listens on port 1025 without encryption or authentication.
Capacity and retention: Mailpit reports SMTP ingestion of 100–200 emails per second depending on system and message factors, and by default prunes messages to keep the most recent 500.
POP3 limit: The optional POP3 service makes only the latest 100 messages available for performance reasons.
Intended users: Mailpit is aimed at developers testing email functionality without sending messages to real email addresses.
Project history: Mailpit was first released on July 30, 2022.
Price from: Free

Where it ranks on Freedom251

Best Email Testing Software in 2026#1 of 28

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Sources

mailpit.axllent.org/about/· checked 4 Oct 2026
mailpit.axllent.org/docs/· checked 4 Oct 2026
mailpit.axllent.org/docs/api-v1/· checked 4 Oct 2026
mailpit.axllent.org/docs/integration/webhook/· checked 4 Oct 2026
mailpit.axllent.org/docs/install/· checked 4 Oct 2026
mailpit.axllent.org/docs/configuration/ui-security-policies· checked 4 Oct 2026
mailpit.axllent.org/docs/configuration/smtp/· checked 4 Oct 2026
mailpit.axllent.org/docs/configuration/pop3/· checked 4 Oct 2026
mailpit.axllent.org· checked 4 Oct 2026
mailpit.axllent.org/docs/usage/html-check/· checked 4 Oct 2026
mailpit.axllent.org/docs/usage/link-check/· checked 4 Oct 2026
mailpit.axllent.org/docs/configuration/troubleshooting/· checked 4 Oct 2026