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6 self-hosted options

Self-hosted alternatives to Mailgun

The best open-source alternative to Mailgun is Postal (MIT, 16,893 GitHub stars, Docker image). Stalwart Mail Server stands out for the most commits in the last 12 months (715), and Maddy Mail Server follows.

Forward Email is also listed but is source-available, so it comes after the open-source picks.

About Mailgun: An email API for sending, receiving and tracking transactional mail.

Updated · data from GitHub, refreshed daily

Top picks

  1. Rank 1:

    Postal

    postalserver/postal

    Complete and fully featured mail server for use by websites & web servers.

    Active · last commit Oct 20, 2026

    Email ServersRubyDocker

    Stands out for the most GitHub stars.

  2. Rank 2:

    Stalwart Mail Server

    stalwartlabs/stalwart

    All-in-one mail server with JMAP, IMAP4, and SMTP support and a wide range of modern features.

    Active · last commit Oct 20, 2026

    Email ServersRustDocker

    Stands out for the most commits in the last 12 months (715).

  3. Rank 3:

    Maddy Mail Server

    foxcpp/maddy

    All-in-one mail server that implements SMTP (both MTA and MX) and IMAP. Replaces Postfix, Dovecot, OpenDKIM, OpenSPF, OpenDMARC with single daemon.

    Active · last commit Oct 20, 2026

    Email ServersGo

At a glance

Mailgun alternatives compared

Open-source apps come first, then source-available ones and apps whose license appsgit could not verify; within each group, projects with at least 12 commits in the last 12 months come before less active or archived ones, then by GitHub stars.

Mailgun alternatives compared, data as of 2026-10-26
AppStands out forLicenseGitHub starsCommits (12 mo)Last commitDocker image
Postalthe most GitHub starsMIT16,89318Oct 20, 2026Yes
Stalwart Mail Serverthe most commits in the last 12 months (715)AGPL-3.015,298715Oct 20, 2026Yes
Maddy Mail Server–GPL-3.06,11590Oct 20, 2026No
Moxa permissive MIT licenseMIT5,91896Oct 9, 2026No
Harakaits JavaScript codebaseMIT5,62790Oct 17, 2026No
Forward Email–source-available, BSL 1.1 (a few files MPL-2.0)1,6911,461Oct 26, 2026Yes

Full list

All 6 Mailgun alternatives

Open any app for live stats, license details and a deploy option.

  1. 1

    Postal

    Complete and fully featured mail server for use by websites & web servers.

    Stands out for the most GitHub stars. Postal has 16,893 GitHub stars, uses the MIT license, ships a Docker image and had 18 commits in the last year.

  2. 2

    Stalwart Mail Server

    All-in-one mail server with JMAP, IMAP4, and SMTP support and a wide range of modern features.

    Stands out for the most commits in the last 12 months (715). Stalwart Mail Server has 15,298 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 715 commits in the last year.

  3. 3

    Maddy Mail Server

    All-in-one mail server that implements SMTP (both MTA and MX) and IMAP. Replaces Postfix, Dovecot, OpenDKIM, OpenSPF, OpenDMARC with single daemon.

    Maddy Mail Server has 6,115 GitHub stars, uses the GPL-3.0 license and had 90 commits in the last year.

  4. 4

    Mox

    Complete e-mail solution with IMAP4, SMTP, SPF, DKIM, DMARC, MTA-STS, DANE and DNSSEC, reputation-based and content-based junk filtering, Internationalization (IDNA), automatic TLS with ACME and…

    Stands out for a permissive MIT license. Mox has 5,918 GitHub stars, uses the MIT license and had 96 commits in the last year.

  5. 5

    Haraka

    Fast, highly extensible, and event driven SMTP server.

    Stands out for its JavaScript codebase. Haraka has 5,627 GitHub stars, uses the MIT license and had 90 commits in the last year.

  6. 6

    Forward Email

    Privacy-focused encrypted email for everyone. All-in-one alternative to Gmail + Mailchimp + Sendgrid.

    Forward Email has 1,691 GitHub stars, is source-available under the BSL 1.1 (a few files MPL-2.0) (not an open-source license), ships a Docker image and had 1,461 commits in the last year.

FAQ

Mailgun alternatives: FAQ

Still curious? Email info@appsgit.com.

Is there a free alternative to Mailgun?

Yes. 5 of the 6 apps on this page are open source; 1 is source-available. The open-source ones are free to self-host without per-user fees; source-available licenses add conditions such as user caps or limits on hosted use, so read them before you commit.

Can I self-host an alternative to Mailgun with Docker?

Yes. 3 of the 6 apps here publish a Docker image, including Postal, Stalwart Mail Server and Forward Email (source-available), so you can run them on a home server or VPS with Docker Compose.

Which Mailgun alternative is the most actively developed?

Forward Email (source-available) (source-available, BSL 1.1 (a few files MPL-2.0)), with 1,461 commits in the last 12 months. Activity is a good sign that bugs and security issues get fixed.

How is this list ranked?

Open-source apps come first, then source-available ones and apps whose license appsgit could not verify; within each group, projects with at least 12 commits in the last 12 months come before less active or archived ones, then by GitHub stars.