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10 top picks · 3 audience rankings

Best open source email servers

The best open source email server is Stalwart Mail Server, with 14,971 GitHub stars, the AGPL-3.0 license and a Docker image; Mailcow and docker-mailserver are strong alternatives. This page also breaks the picks down by team size and use: docker-mailserver leads for startups; Stalwart Mail Server for small business and enterprise. The overall ranking weighs GitHub stars, commits in the last year, Docker images, open-source licenses and recent commits across the 24 apps in the email servers category of the appsgit catalog.

Updated · data from GitHub, refreshed nightly

Top picks

  1. Rank 1:

    Stalwart Mail Server

    stalwartlabs/stalwart

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

    Email ServersRustDocker

    Stalwart Mail Server has 14,971 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 679 commits in the last year; it replaces Twilio SendGrid and Mailgun.

  2. Rank 2:

    Mailcow

    mailcow/mailcow-dockerized

    Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration.

    Email ServersJavaScriptDocker

    Mailcow has 13,563 GitHub stars, uses the GPL-3.0 license, ships a Docker image and had 316 commits in the last year; it replaces Google Workspace and Microsoft 365.

  3. Rank 3:

    docker-mailserver

    docker-mailserver/docker-mailserver

    Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container. Only configuration files, no SQL database.

    Email ServersShellDocker

    docker-mailserver has 18,903 GitHub stars, uses the MIT license, ships a Docker image and had 107 commits in the last year; it replaces Gmail.

1 of 4 · 10 picks

Top picks

10 of the 24 apps in the email servers category, ranked on GitHub stars, commits in the last year, Docker images, open-source licenses and recent commits.

  1. 1

    Stalwart Mail Server

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

    Stalwart Mail Server has 14,971 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 679 commits in the last year; it replaces Twilio SendGrid and Mailgun.

  2. 2

    Mailcow

    Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration.

    Mailcow has 13,563 GitHub stars, uses the GPL-3.0 license, ships a Docker image and had 316 commits in the last year; it replaces Google Workspace and Microsoft 365.

  3. 3

    docker-mailserver

    Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container. Only configuration files, no SQL database.

    docker-mailserver has 18,903 GitHub stars, uses the MIT license, ships a Docker image and had 107 commits in the last year; it replaces Gmail.

  4. 4

    Postal

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

    Postal has 16,854 GitHub stars, uses the MIT license, ships a Docker image and had 18 commits in the last year; it replaces Twilio SendGrid and Mailgun.

  5. 5

    SimpleLogin

    Open source email alias solution to protect your email address. Comes with browser extensions and mobile apps.

    SimpleLogin has 7,037 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 250 commits in the last year.

  6. 6

    Mailu

    Simple yet full-featured mail server as a set of Docker images.

    Mailu has 7,537 GitHub stars, uses the MIT license, ships a Docker image and had 169 commits in the last year; it replaces Gmail.

  7. 7

    Roundcube

    Browser-based IMAP client with an application-like user interface.

    Roundcube has 7,207 GitHub stars, uses the GPL-3.0 license and had 260 commits in the last year; it replaces Gmail.

  8. 8

    Mail-in-a-Box

    Turns any Ubuntu server into a fully functional mail server with one command.

    Mail-in-a-Box has 15,435 GitHub stars, uses the CC0-1.0 license and had 20 commits in the last year; it replaces Gmail.

  9. 9

    AnonAddy

    Email forwarding service for creating aliases.

    AnonAddy has 4,885 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 67 commits in the last year.

  10. 10

    Modoboa

    Mail hosting and management platform including a modern and simplified web user interface.

    Modoboa has 3,542 GitHub stars, uses the ISC license and had 765 commits in the last year.

2 of 4 · 5 picks

Best for startups

Ranked for startups on GitHub stars, commits in the last year, Docker images, open-source licenses, project websites and recent commits.

  1. 1

    docker-mailserver

    Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container. Only configuration files, no SQL database.

    docker-mailserver has 18,903 GitHub stars, uses the MIT license, ships a Docker image and had 107 commits in the last year; it replaces Gmail. For startups it also scores on a Docker image, a permissive license (MIT), a project website and a commit in the last 90 days.

  2. 2

    Stalwart Mail Server

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

    Stalwart Mail Server has 14,971 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 679 commits in the last year; it replaces Twilio SendGrid and Mailgun. For startups it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  3. 3

    Mailcow

    Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration.

    Mailcow has 13,563 GitHub stars, uses the GPL-3.0 license, ships a Docker image and had 316 commits in the last year; it replaces Google Workspace and Microsoft 365. For startups it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  4. 4

    Postal

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

    Postal has 16,854 GitHub stars, uses the MIT license, ships a Docker image and had 18 commits in the last year; it replaces Twilio SendGrid and Mailgun. For startups it also scores on a Docker image, a permissive license (MIT), a project website and a commit in the last 90 days.

  5. 5

    Mailu

    Simple yet full-featured mail server as a set of Docker images.

    Mailu has 7,537 GitHub stars, uses the MIT license, ships a Docker image and had 169 commits in the last year; it replaces Gmail. For startups it also scores on a Docker image, a permissive license (MIT), a project website and a commit in the last 90 days.

3 of 4 · 5 picks

Best for small business

Ranked for small business on GitHub stars, commits in the last year, Docker images, open-source licenses, project websites, recent commits and deploy guides.

  1. 1

    Stalwart Mail Server

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

    Stalwart Mail Server has 14,971 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 679 commits in the last year; it replaces Twilio SendGrid and Mailgun. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  2. 2

    Mailcow

    Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration.

    Mailcow has 13,563 GitHub stars, uses the GPL-3.0 license, ships a Docker image and had 316 commits in the last year; it replaces Google Workspace and Microsoft 365. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  3. 3

    docker-mailserver

    Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container. Only configuration files, no SQL database.

    docker-mailserver has 18,903 GitHub stars, uses the MIT license, ships a Docker image and had 107 commits in the last year; it replaces Gmail. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  4. 4

    Postal

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

    Postal has 16,854 GitHub stars, uses the MIT license, ships a Docker image and had 18 commits in the last year; it replaces Twilio SendGrid and Mailgun. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  5. 5

    SimpleLogin

    Open source email alias solution to protect your email address. Comes with browser extensions and mobile apps.

    SimpleLogin has 7,037 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 250 commits in the last year. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

4 of 4 · 5 picks

Best for enterprise

Ranked for enterprise on GitHub stars, commits in the last year, open-source licenses and recent commits.

  1. 1

    Stalwart Mail Server

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

    Stalwart Mail Server has 14,971 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 679 commits in the last year; it replaces Twilio SendGrid and Mailgun. For enterprise it also scores on an open-source license and a commit in the last 90 days.

  2. 2

    docker-mailserver

    Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container. Only configuration files, no SQL database.

    docker-mailserver has 18,903 GitHub stars, uses the MIT license, ships a Docker image and had 107 commits in the last year; it replaces Gmail. For enterprise it also scores on an open-source license and a commit in the last 90 days.

  3. 3

    Mailcow

    Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration.

    Mailcow has 13,563 GitHub stars, uses the GPL-3.0 license, ships a Docker image and had 316 commits in the last year; it replaces Google Workspace and Microsoft 365. For enterprise it also scores on an open-source license and a commit in the last 90 days.

  4. 4

    Postal

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

    Postal has 16,854 GitHub stars, uses the MIT license, ships a Docker image and had 18 commits in the last year; it replaces Twilio SendGrid and Mailgun. For enterprise it also scores on an open-source license and a commit in the last 90 days.

  5. 5

    Mail-in-a-Box

    Turns any Ubuntu server into a fully functional mail server with one command.

    Mail-in-a-Box has 15,435 GitHub stars, uses the CC0-1.0 license and had 20 commits in the last year; it replaces Gmail. For enterprise it also scores on an open-source license and a commit in the last 90 days.

FAQ

Questions and answers

Still curious? Email info@appsgit.com.

What is the best open source email server?

The best open source email server is Stalwart Mail Server, with 14,971 GitHub stars, the AGPL-3.0 license and a Docker image; Mailcow and docker-mailserver are strong alternatives. This page also breaks the picks down by team size and use: docker-mailserver leads for startups; Stalwart Mail Server for small business and enterprise. The overall ranking weighs GitHub stars, commits in the last year, Docker images, open-source licenses and recent commits across the 24 apps in the email servers category of the appsgit catalog.

Is Stalwart Mail Server free?

Yes. Stalwart Mail Server is open-source software released under the AGPL-3.0 license, so you can self-host it at no cost. You only pay for the server it runs on, and some projects also offer an optional paid cloud plan.

Which open source email server is best for a startup?

docker-mailserver ranks first for startups, with 18,903 GitHub stars, the MIT license and a Docker image; Stalwart Mail Server and Mailcow follow. The startups ranking adds points for Docker images, permissive licenses, project websites and recent commits on top of stars and activity.

Which open source email server is best for a small business?

Stalwart Mail Server ranks first for small business, with 14,971 GitHub stars, the AGPL-3.0 license and a Docker image; Mailcow and docker-mailserver follow. The small business ranking adds points for Docker images, open-source licenses, project websites, recent commits and deploy guides on top of stars and activity.

Can I self-host these email servers with Docker?

Yes, 7 of the 10 picks. Stalwart Mail Server, Mailcow and docker-mailserver publish Docker images, so you can run them on a VPS or home server with Docker Compose. The others install from their own packages or source; follow each project's install guide.

Are all of these email servers open source?

All 10 apps on this list are open source. You can self-host and modify each one under its license.

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