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Open-source alternatives to Postmark

Compare community-driven replacements for Postmark in mail servers & relays workflows. We curate active, self-hostable options with transparent licensing so you can evaluate the right fit quickly.

Postmark logo

Postmark

Postmark specializes in fast, reliable transactional email delivery with high deliverability rates, detailed analytics, and developer-friendly APIs focused on application emails.Read more
Mail Servers & Relays
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Key stats

  • 6Alternatives
  • 2Support self-hosting

    Run on infrastructure you control

  • 5Active development

    Recent commits in the last 6 months

  • 2Permissive licenses

    MIT, Apache, and similar licenses

Counts reflect projects currently indexed as alternatives to Postmark.

All open-source alternatives

useSend logo

useSend

Self‑hosted email platform delivering reliable, low‑cost SES mail

Self-host friendlyActive developmentPrivacy-firstTypeScript

Why teams choose it

  • Dashboard with delivery, open, click, and bounce metrics
  • REST and scheduled API for transactional and marketing emails
  • SMTP endpoint compatible with existing tools

Watch for

Beta stage may lack stability

Migration highlight

Transactional order confirmations

Deliver reliable order emails with real‑time open tracking

Haraka logo

Haraka

High-performance Node.js SMTP server with modular plugin architecture

Active developmentPermissive licenseIntegration-friendlyJavaScript

Why teams choose it

  • Handles thousands of concurrent connections with asynchronous Node.js performance
  • Modular plugin architecture for spam filtering, authentication, DKIM signing, and custom logic
  • Built-in outbound mail delivery engine with automatic queueing for relay messages

Watch for

Not a complete mail solution—requires separate systems for storage, IMAP, and local delivery

Migration highlight

Spam Filtering Gateway

Deploy Haraka in front of Exchange or Postfix to filter incoming mail through SpamAssassin, DNSBL checks, and custom rules before delivery to the mail store.

Tuta logo

Tuta

Secure email with seamless end-to-end encryption across devices

Active developmentPrivacy-firstAI-powered workflowsTypeScript

Why teams choose it

  • End-to-end encryption for email, contacts, and calendar
  • Cross‑platform clients: web, desktop, and iOS
  • Open‑source code released under GPL‑3.0

Watch for

Requires internet connectivity for synchronization

Migration highlight

Secure personal correspondence

All personal emails are encrypted end‑to‑end, protecting them from interception.

Plunk logo

Plunk

Self-hosted email platform powered by AWS SES

Self-host friendlyActive developmentPrivacy-firstTypeScript

Why teams choose it

  • Transactional email API integrated with AWS SES
  • Automation workflows triggered by user actions
  • Broadcast capability for newsletters and product updates

Watch for

Tied to AWS SES pricing and limits

Migration highlight

Order confirmation emails

Send reliable transactional messages instantly after purchase, ensuring customers receive receipts.

Go-Guerrilla logo

Go-Guerrilla

Lightweight SMTP server for high-volume email reception in Go

Permissive licenseIntegration-friendlyAI-powered workflowsGo

Why teams choose it

  • Multi-server architecture with shared backend for horizontal scaling
  • Hot-reloadable configuration without service interruption
  • Chainable processor system for MySQL, Redis, MailDir, and custom backends

Watch for

Project was abandoned by original maintainer, now community-maintained

Migration highlight

Disposable Email Service

Receive millions of temporary emails daily, parse headers, store bodies in Redis, and log metadata to MySQL for fast retrieval

Maddy logo

Maddy

Composable all-in-one mail server replacing multiple daemons

Active developmentFast to deployAI-powered workflowsGo

Why teams choose it

  • Single daemon handling SMTP, MX, and IMAP
  • Built‑in DKIM, SPF, DMARC, DANE, and MTA‑STS support
  • Unified declarative configuration

Watch for

IMAP storage is still in beta

Migration highlight

Unified mail server for a startup

Simplified setup and reduced operational cost

Choosing a mail servers & relays alternative

Teams replacing Postmark in mail servers & relays workflows typically weigh self-hosting needs, integration coverage, and licensing obligations.

  • 2 projects let you self-host and keep customer data on infrastructure you control.
  • 5 options are actively maintained with recent commits.

Tip: shortlist one hosted and one self-hosted option so stakeholders can compare trade-offs before migrating away from Postmark.