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Open-source alternatives to MailerSend

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

MailerSend logo

MailerSend

MailerSend is an email delivery service focused on high deliverability, easy integration via API/SMTP, custom templates, team management, and support for transactional and marketing emails.Read more
Mail Servers & Relays
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Key stats

  • 8Alternatives
  • 3Support self-hosting

    Run on infrastructure you control

  • 6Active development

    Recent commits in the last 6 months

  • 5Permissive licenses

    MIT, Apache, and similar licenses

Counts reflect projects currently indexed as alternatives to MailerSend.

All open-source alternatives

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.

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

Mailu logo

Mailu

Fully featured Docker‑based mail server that's simple to deploy

Active developmentPrivacy-firstFast to deployPython

Why teams choose it

  • Standard email protocols with auto‑configuration (IMAP, IMAP+, SMTP, Submission)
  • Built‑in anti‑spam and security (DKIM, DMARC, TLS, DANE, LetsEncrypt, virus scanning)
  • Webmail and admin UI with multi‑domain and quota management

Watch for

Requires familiarity with Docker and container orchestration

Migration highlight

Deploy a company mail system in minutes

Launch IMAP/SMTP services with webmail and admin UI using a single docker‑compose file.

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.

Zero logo

Zero

Self-hosted AI-enhanced email client with unified inbox

Self-host friendlyPermissive licensePrivacy-firstTypeScript

Why teams choose it

  • Open‑source with full transparency
  • AI‑driven email assistants and LLM integration
  • Unified inbox across Gmail, Outlook and other providers

Watch for

Requires technical knowledge to set up and maintain

Migration highlight

Consolidate corporate mailboxes

All employee Gmail and Outlook accounts appear in a single searchable inbox, reducing context switching.

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.

Mail-in-a-Box logo

Mail-in-a-Box

One-click, self-hosted email server that just works

Self-host friendlyActive developmentPermissive licensePython

Why teams choose it

  • One‑click installation on fresh Ubuntu 22.04
  • Automatic TLS via Let’s Encrypt for all services
  • Integrated DNS with SPF, DKIM, DMARC, DNSSEC

Watch for

Limited customization – no power‑user options

Migration highlight

Personal email domain

Run your own address (you@yourdomain.com) with spam filtering and encrypted connections, eliminating reliance on third‑party providers.

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

Choosing a mail servers & relays alternative

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

  • 3 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 MailerSend.