Mailpit vs MailHog vs Inbucket 2026: Local SMTP Catch-All Servers

TL;DR

If you're starting a new project in 2026, use Mailpit. It's MailHog's spiritual successor — same UX, actively maintained, faster, and shipping the features (HTML preview, link checks, REST API, message tagging) that MailHog stopped getting. MailHog still works but hasn't seen meaningful releases in years. Inbucket is the underrated third option that supports POP3 and acts as a real multi-user mailbox simulator — useful when your tests need to fetch mail, not just observe it.

Key Takeaways

• Mailpit — Go, MIT, ~6K stars, single binary, actively developed by axllent; the de facto MailHog replacement
• MailHog — Go, MIT, ~13K stars, last meaningful release 2020; still functional for simple needs
• Inbucket — Go, MIT, ~2K stars, supports SMTP + POP3 + HTTP; multi-mailbox by design
• All three are single binaries, run in Docker, and intercept SMTP traffic instead of relaying it
• Best fit: Mailpit for "drop-in MailHog replacement"; MailHog only if you have a working setup you don't want to touch; Inbucket when tests need to fetch via POP3

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What These Tools Do

These are all "fake SMTP" servers. You point your application's mail config at them (host, port, no auth or fake auth), they accept everything you send, and they show you the captured emails in a web UI. They never actually deliver anything to the outside world. They are how you safely run development environments and integration tests without spamming real users.

The category overlaps with services like Mailtrap and Ethereal Mail — those are SaaS; these three are open source local options.

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Decision Table

Capability	Mailpit	MailHog	Inbucket
License	MIT	MIT	MIT
Last release	Active 2025–2026	2020 (mostly)	Active 2025–2026
Single binary	✅	✅	✅
Web UI	✅ (modern)	✅ (dated but functional)	✅ (modern)
HTML email preview	✅	✅	✅
Plain text view	✅	✅	✅
Source view	✅	✅	✅
Link checker	✅	❌	❌
HTML/CSS validator	✅	❌	❌
Spam analysis (SpamAssassin)	✅	⚠️ (basic)	❌
REST API	✅	✅	✅
WebSocket live updates	✅	✅	✅
POP3 support	❌	❌	✅
Multi-mailbox (per recipient)	⚠️ (filter)	❌	✅ (first-class)
Tags / labels	✅	❌	❌
Memory footprint	~15 MB	~15 MB	~15 MB
Persistence	SQLite (optional)	In-memory or BoltDB	In-memory or filesystem

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Mailpit: The Default Choice

Mailpit was created by axllent in 2022 specifically to fill the void left by MailHog's stalled development. The UX is intentionally MailHog-like, so anyone moving from MailHog feels at home immediately, but the engine is rewritten and the feature set has continued to grow.

Strengths

• Active development; releases multiple times per quarter through 2025–2026
• Modern UI with dark mode, keyboard shortcuts, and message search
• Built-in HTML link checker — flags broken links in the email before your users see them
• HTML/CSS validation pass — catches "this won't render in Outlook" issues
• Optional SpamAssassin integration for header analysis
• Persistent SQLite storage means messages survive restarts (configurable retention)
• REST API is more complete than MailHog's; supports tagging, search, and bulk operations
• Chaos mode injects errors (delays, rejected recipients) to test failure paths

Weaknesses

• POP3 not supported — if your test pipeline needs to fetch mail, choose Inbucket
• Multi-recipient mailbox semantics work but aren't as natural as Inbucket's

If you're updating a project that uses MailHog, the migration is one line in docker-compose.yml. The SMTP and HTTP ports can be the same; your application code doesn't change.

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MailHog: The Legacy Default

MailHog was the standard for years and earned its place. The reason it remains so prevalent is straightforward: it works, it's been baked into hundreds of project templates, and migrating away takes deliberate effort.

Strengths

• Massive install base; nearly every Laravel/Rails/Symfony tutorial mentions it
• Single binary, trivial to run
• BoltDB-based persistence is reliable

Weaknesses

• The project has not seen major activity since 2020
• Open issues for known problems (CSP, security headers, modern Outlook rendering) remain unresolved
• The UI looks every bit its age
• No active maintainer to address security disclosures

Use MailHog if you have a working setup and no specific feature you're missing. For greenfield work, prefer Mailpit.

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Inbucket: The Multi-Mailbox Option

Inbucket is the option that actually behaves like a real mail server with mailboxes. Each recipient address has its own inbox, fetchable over POP3 in addition to the HTTP UI.

Strengths

• POP3 support — the only one of the three. Critical when you're testing systems that fetch mail (e.g., Mautic, self-hosted help desks, ticket systems pulling email-to-ticket)
• Per-recipient mailboxes are first-class, not a filter on a single store
• Modern UI; active development
• Greylisting and basic anti-abuse features for development environments that get accidentally exposed

Weaknesses

• Smaller community than Mailpit/MailHog; fewer tutorials
• HTML rendering quality is good but not at Mailpit's link-checker level
• No SpamAssassin integration

If your tests run a workflow like "send invoice → ticket system fetches via POP3 → creates support ticket," Inbucket is the right tool — neither Mailpit nor MailHog can play the POP3 server role.

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Docker Compose Snippets

A drop-in service for Mailpit:

mailpit:
  image: axllent/mailpit:latest
  restart: unless-stopped
  ports:
    - "1025:1025"  # SMTP
    - "8025:8025"  # HTTP UI
  environment:
    MP_MAX_MESSAGES: 5000
    MP_DATABASE: /data/mailpit.db
  volumes:
    - mailpit_data:/data

Inbucket is similarly minimal:

inbucket:
  image: inbucket/inbucket:latest
  restart: unless-stopped
  ports:
    - "1025:2500"  # SMTP
    - "1100:1100"  # POP3
    - "9000:9000"  # HTTP UI

Either drops cleanly into the typical Laravel/Rails/Django/Node dev stack. If you maintain a collection of compose templates, Mailpit is the right default for any new template.

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When to Use Which Layer

A common pattern:

• Local development: Mailpit. Every developer has it running on localhost:8025.
• CI integration tests: Mailpit, with the SQLite store enabled so the test runner can assert against persisted messages via the REST API.
• Tests that need POP3 fetch: Inbucket. Same SMTP port, but the mailbox is fetchable.
• Staging environments: Mailpit again, often with SpamAssassin enabled to catch problematic email content before it hits production
• Production: None of these. You want a real provider — see open source alternatives to SendGrid or Postal as a self-hosted Mailgun alternative.

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Migration: MailHog → Mailpit

Almost mechanical:

1. Replace the mailhog/mailhog image with axllent/mailpit in your docker-compose.yml
2. Update the UI port mapping if you want the conventional 8025 (Mailpit defaults to it)
3. SMTP port is 1025 for both, no app-side change needed
4. If you scripted against MailHog's API, the Mailpit API has compatible endpoints for the basics; check Mailpit's docs for the small naming differences

Most teams complete the migration in under 15 minutes.

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Who Should Choose What

Choose Mailpit if:

• You're starting a new project today
• You're modernizing a stack that has MailHog baked in
• You want active development, link checking, and modern UI

Stick with MailHog if:

• You have a working setup with no specific need it doesn't serve
• You want to make zero changes for the next year

Choose Inbucket if:

• You need POP3 (your application fetches mail rather than just sending it)
• You want true per-recipient mailboxes for end-to-end test scenarios
• You're testing a help-desk or email-to-ticket workflow

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Verdict

In 2026, Mailpit is the right default for nearly every team. MailHog is a stable, frozen tool — fine to keep but not where new energy belongs. Inbucket fills the genuine niche of "I need to fetch mail in tests, not just inspect it." Pick by behavior you need, not by familiarity, and your CI runs will be more reliable for it.

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Related: Open source alternatives to SendGrid · How to self-host Postal · Docker Compose templates.