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Open-source alternatives to Mailgun

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

Mailgun logo

Mailgun

Mailgun provides APIs and SMTP to send and receive transactional emails at scale, with features like inbound routing, webhooks, suppression lists, templates, analytics, and email validation. It supports dedicated IPs and domain management to improve deliverability and control.Read more
Mail Servers & Relays
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Key stats

  • 8Alternatives
  • 4Support self-hosting

    Run on infrastructure you control

  • 6Active development

    Recent commits in the last 6 months

  • 4Permissive licenses

    MIT, Apache, and similar licenses

Counts reflect projects currently indexed as alternatives to Mailgun.

All open-source alternatives

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.

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.

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

Mautic logo

Mautic

Open source marketing automation software you control completely

Self-host friendlyActive developmentPrivacy-firstPHP

Why teams choose it

  • Self-hosted deployment with complete data ownership and no vendor lock-in
  • Multi-channel campaigns across email, SMS, social media, and web without extra costs
  • Unlimited contact segmentation and marketing automation workflows

Watch for

Requires technical expertise for installation, configuration, and ongoing maintenance

Migration highlight

Privacy-Compliant Lead Nurturing

Healthcare organizations automate GDPR-compliant email sequences while maintaining full data sovereignty on private infrastructure

Postal logo

Postal

Self‑hosted mail server for inbound and outbound email.

Active developmentPermissive licensePrivacy-firstRuby

Why teams choose it

  • Handles inbound and outbound email at scale
  • Self‑hosted deployment via Docker or native Ruby
  • Extensive documentation and CLI tools

Watch for

Requires own server infrastructure and maintenance

Migration highlight

Transactional email for web applications

Reliable delivery of password resets, order confirmations, and notifications without third‑party fees.

SendPortal logo

SendPortal

Self-hosted email marketing platform with campaign tracking and automation

Self-host friendlyPermissive licensePrivacy-firstPHP

Why teams choose it

  • Multi-workspace architecture for managing campaigns across multiple brands or clients
  • Native integration with five major email service providers (SES, Postmark, Sendgrid, Mailgun, Mailjet)
  • Comprehensive tracking and reporting for subscriber engagement and campaign performance

Watch for

Requires PHP 8.2+ and Laravel 10+ infrastructure management expertise

Migration highlight

Agency Multi-Client Management

Digital agencies use multi-workspace support to manage separate email campaigns for dozens of clients from a single installation, reducing per-client tooling costs.

Choosing a mail servers & relays alternative

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

  • 4 projects let you self-host and keep customer data on infrastructure you control.
  • 6 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 Mailgun.