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Best Open-Source SendGrid Alternatives (2026)

15 self-hostable projects that directly address SendGrid — without per-email costs at scale. The shortlist is manually checked for product fit before we compare self-host difficulty, deploy paths, maintenance, and licensing.

SendGrid charges per email, so transactional and marketing volume that's cheap at small scale becomes a meaningful line item as you grow. Running your own SMTP delivery platform turns that per-email cost into fixed infrastructure you control.

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Our picks at a glance

Easiest to self-host
MailDev

Difficulty 2/5 — but note it's a local testing SMTP server with a web UI, not a production sender.

Most powerful
Postal

A complete self-hosted mail delivery platform positioned directly as a SendGrid/Mailgun alternative.

Most active
Postal

At ~16,600 stars it edges out the rest in momentum.

Best managed option
Forward Email

It's the only option here with a managed offering (managed:yes).

Compare the 15 reviewed alternatives

ProjectDeployManagedLicense
listmonk
Go
24k ★
3/5
Moderate
Docker
Docker Compose
+1
AGPL-3.02 days agoRepo
Postal
Ruby
17k ★
4/5
Involved
Docker
Docker Compose
+1
MIT6 days agoRepo
Mail-in-a-Box
Shell
15k ★
2/5
Simple
Manual
CC0-1.04 days agoRepo
Stalwart Mail Server
Rust
15k ★
3/5
Moderate
Docker
Docker Compose
+1
AGPL-3.06 days agoRepo
MailDev
JavaScript
6.2k ★
2/5
Simple
Docker
Manual
MIT1 month agoRepo
Maddy Mail Server
Go
6.1k ★
4/5
Involved
Docker
Manual
GPL-3.06 days agoRepo
Mox
Go
5.9k ★
3/5
Moderate
Manual
MIT17 days agoRepo
Mailtrain
JavaScript
5.8k ★
3/5
Moderate
Docker
Docker Compose
+1
GPL-3.01 year agoRepo
Haraka
JavaScript
5.6k ★
4/5
Involved
Docker
Manual
MIT9 days agoRepo
Modoboa
Python
3.5k ★
4/5
Involved
Docker
Manual
ISCtodayRepo
SendPortal
PHP
2.2k ★
2/5
Simple
Docker
Manual
AGPL-3.04 days agoRepo
wildduck
Nodejs
2.1k ★
5/5
Advanced
Docker
Manual
EUPL-1.2todayRepo
iRedMail
Shell
1.8k ★
3/5
Moderate
Manual
GPL-3.07 days agoRepo
Forward Email
JavaScript
1.7k ★
5/5
Advanced
Manual
BUSL-1.1todayRepo
Sendy
PHP
100 ★
2/5
Simple
Docker
Manual
Proprietary5 months agoRepo

What to look for: Be clear whether you need production delivery (real outbound SMTP with reputation management) or just local testing — those are very different tools. For production, focus on deliverability, queuing, retries, and IP/domain warm-up; SPF/DKIM/DMARC setup is on you.

Head-to-head:listmonk vs SendGridPostal vs SendGridMail-in-a-Box vs SendGridStalwart Mail Server vs SendGridMailDev vs SendGrid

The alternatives, reviewed

  1. #1
    listmonk
    Self-host: Moderate

    High-performance self-hosted newsletter and mailing list manager

    24k Go AGPL-3.0 2 days ago
    How it compares to SendGrid
    • No built-in marketing automation/journey builder like Mailchimp
    • No bundled deliverability/IP reputation management — you supply your own SMTP/SES
    • No native landing page or e-commerce/CRM integrations
    • Reporting and analytics are basic compared to commercial suites
    RepoDetails & deploy →
  2. #2
    Postal
    Self-host: Involved

    Self-hosted mail delivery platform, a SendGrid/Mailgun alternative

    17k Ruby MIT 6 days ago
    How it compares to SendGrid
    • You are responsible for IP reputation, warmup, and deliverability
    • Requires MariaDB, RabbitMQ, and DNS/DKIM configuration to run
    • No marketing-campaign UI — it is a delivery engine, not a newsletter builder
    • Less hand-holding than managed providers for spam/blocklist issues
    RepoDetails & deploy →
  3. #3
    Mail-in-a-Box
    Self-host: Simple

    Turn any Ubuntu VPS into a complete, self-hosted mail server in one command

    15k Shell CC0-1.0 4 days ago
    How it compares to SendGrid
    • Requires a dedicated Ubuntu VPS with a clean IP reputation; shared hosting is not supported
    • No built-in bulk mailing or newsletter campaign tools
    • Limited horizontal scalability; single-server architecture only
    • Webmail (Roundcube) is functional but far less polished than Gmail's UI
    RepoDetails & deploy →
  4. #4
    Stalwart Mail Server
    Self-host: Moderate

    Modern all-in-one mail server with JMAP, IMAP4, and SMTP in a single Rust binary

    15k Rust AGPL-3.0 6 days ago
    How it compares to SendGrid
    • No built-in newsletter/broadcast campaign tooling
    • Web admin UI is functional but less refined than commercial email service dashboards
    • Third-party anti-virus (ClamAV) integration requires additional setup
    • Community support only on the free tier; paid support plans are limited
    RepoDetails & deploy →
  5. #5
    MailDev
    Self-host: Simple

    Local SMTP server with a web UI to test app-generated email

    6.2k JavaScript MIT 1 month ago
    How it compares to SendGrid
    • A development/testing catcher only — not for sending real production email
    • No deliverability, analytics, or campaign features
    • Not intended as a long-running production mail service
    • Limited storage/persistence for captured messages
    RepoDetails & deploy →
  6. #6
    Maddy Mail Server
    Self-host: Involved

    Single-binary Go mail server replacing Postfix, Dovecot, OpenDKIM, and OpenDMARC

    6.1k Go GPL-3.0 6 days ago
    How it compares to SendGrid
    • No webmail interface; users need a separate IMAP client
    • Documentation is less comprehensive than established stacks like Postfix + Dovecot
    • No built-in web admin panel for managing accounts
    • Smaller ecosystem and community compared to traditional mail server components
    RepoDetails & deploy →
  7. #7
    Mox
    Self-host: Moderate

    Complete, modern self-hosted email server with JMAP, DANE, and built-in junk filtering

    5.9k Go MIT 17 days ago
    How it compares to SendGrid
    • No Docker image provided officially; manual binary deployment only
    • Not designed for high-volume transactional or bulk email sending
    • Admin UI and webmail are functional but lack polish compared to hosted solutions
    • Relatively young project; some edge-case RFC compliance gaps may exist
    RepoDetails & deploy →
  8. #8
    Mailtrain
    Self-host: Moderate

    Self-hosted newsletter app built on Node.js with advanced list management

    5.8k JavaScript GPL-3.0 1 year ago
    How it compares to SendGrid
    • Development activity has slowed considerably in recent years
    • No built-in drag-and-drop email builder (relies on GrapesJS plugin)
    • Documentation is sparse for v2 features
    RepoDetails & deploy →
  9. #9
    Haraka
    Self-host: Involved

    Fast, highly extensible event-driven SMTP server in Node.js

    5.6k JavaScript MIT 9 days ago
    How it compares to SendGrid
    • Low-level MTA — no web UI, dashboards, or campaign tooling
    • Requires writing/configuring plugins for real-world setups
    • No built-in analytics, tracking, or template management
    • Deliverability and reputation management are entirely on you
    RepoDetails & deploy →
  10. #10
    Modoboa
    Self-host: Involved

    Web-based mail hosting platform with modern UI for managing domains and accounts

    3.5k Python ISC today
    How it compares to SendGrid
    • Still depends on external Postfix and Dovecot daemons; not truly all-in-one
    • Webmail plugin (Rainloop/SOGo) requires separate configuration
    • No bulk mailing or newsletter campaign features
    • Documentation can be incomplete for advanced plugin setups
    RepoDetails & deploy →
  11. #11
    SendPortal
    Self-host: Simple

    Self-hosted email marketing platform built on Laravel

    2.2k PHP AGPL-3.0 4 days ago
    How it compares to SendGrid
    • No visual drag-and-drop email builder included
    • Automation workflows are not yet implemented
    • Limited built-in template library
    RepoDetails & deploy →
  12. #12
    wildduck
    Self-host: Advanced

    Scalable, horizontally distributed IMAP/POP3 mail server with no single point of failure

    2.1k Nodejs EUPL-1.2 today
    How it compares to SendGrid
    • No built-in web admin UI; management is done through a JSON HTTP API only
    • SMTP is a separate component (Haraka/ZoneMTA) requiring additional setup
    • MongoDB dependency adds operational overhead compared to simpler SQL-backed servers
    • Documentation assumes strong Node.js and MongoDB expertise
    RepoDetails & deploy →
  13. #13
    iRedMail
    Self-host: Moderate

    Full-featured open-source mail server built on Postfix and Dovecot, installable in minutes

    1.8k Shell GPL-3.0 7 days ago
    How it compares to SendGrid
    • Full admin panel (iRedAdmin-Pro) requires a paid license; free admin panel is limited
    • Designed for dedicated servers only; Docker or container-based installs are unofficial
    • No built-in newsletter or bulk email campaign features
    • Upgrades between major versions require careful manual steps
    RepoDetails & deploy →
  14. #14
    Forward Email
    Self-host: Advanced

    Privacy-focused email service, an all-in-one Gmail and SaaS alternative

    1.7k JavaScript BUSL-1.1 today
    How it compares to SendGrid
    • Self-hosting is complex and far less documented than the hosted service
    • Newsletter/campaign tooling is thin compared to Mailchimp
    • BUSL-1.1 license is source-available, not fully OSI-open
    • Running production email requires significant infra and DNS expertise
    RepoDetails & deploy →
  15. #15
    Sendy
    Self-host: Simple

    Self-hosted email newsletter app that sends via Amazon SES

    100 PHP Proprietary 5 months ago
    How it compares to SendGrid
    • Requires paid one-time license fee; not truly open source
    • Tightly coupled to AWS SES, limiting provider flexibility
    • No built-in visual email builder; limited automation
    RepoDetails & deploy →

The verdict

For a real SendGrid replacement, Postal is the top pick — it's a full delivery platform built for exactly this and the most active project here. Use MailDev only for local email testing, and Haraka if you want to build custom SMTP routing on a fast, extensible engine.

Still deciding? Compare listmonk vs Postal side by side →

SendGrid alternatives — frequently asked questions

What's the best self-hosted SendGrid alternative?

Postal. It's a complete self-hosted mail delivery platform (~16,600 stars, MIT) positioned as a SendGrid/Mailgun alternative for transactional and bulk sending.

Which one is just for testing emails locally?

MailDev. It's a local SMTP server with a web UI to catch and inspect app-generated email during development — it does not deliver mail to real recipients.

Is there a free open-source SendGrid alternative?

Yes. Postal, MailDev, and Haraka are all MIT-licensed and free. listmonk is AGPL-3.0; Forward Email is BUSL-1.1.

Which alternative is easiest to self-host?

MailDev (difficulty 2/5) is easiest, but it's for testing only. Among production senders, listmonk is 3/5 while Postal and Haraka are 4/5.

Can I send marketing newsletters as well as transactional email?

Postal and Haraka handle transactional/outbound SMTP delivery. listmonk is the better fit for managing newsletters and mailing lists on top of an SMTP relay.

Do any of these offer managed hosting?

Only Forward Email (managed:yes). Postal, MailDev, Haraka, and listmonk are self-host only, so you run and maintain the delivery infrastructure yourself.

Keep exploring

All Email & Newsletters →Self-hosted directory →Easiest to self-host →
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