Open-source email servers and mail delivery platforms

Mail servers you run yourself, for people's mailboxes or for the email your applications send, instead of paying a hosted provider per mailbox or per message.

17 open-source projects, checked against GitHub on 12 November 2026.

All 17 email servers & webmail projects

Showing all 17, ordered by health score.

  1. 86 Active
    Roundcube

    The Roundcube Webmail suite

    GPL-3.0
    Setup
    Docker
    Stars
    7.3k
    Release
    9 November 2026
  2. 85 Active
    Cypht

    Cypht: Lightweight Open Source webmail aggregator [PHP, JS]. Supports IMAP/SMTP, JMAP and EWS (Exchange Web Services)

    LGPL-2.1 relicensed 2020
    Setup
    2 of 5
    Stars
    1.8k
    Release
    6 November 2026
  3. 80 Active
    docker-mailserver

    Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container.

    MIT
    Setup
    1 of 5
    Stars
    19.7k
    Release
    5 November 2026
  4. 80 Active
    wildduck

    Opinionated email server

    EUPL-1.2
    Setup
    2 of 5
    Stars
    2.1k
    Release
    2 November 2026
  5. 76 Active
    Mailu

    Insular email distribution - mail server as Docker images

    MIT
    Setup
    1 of 5
    Stars
    7.6k
    Release
    8 November 2026
  6. 75 Active
    SnappyMail

    Simple, modern & fast web-based email client

    AGPL-3.0 relicensed 2022
    Setup
    3 of 5
    Stars
    1.8k
    Release
    9 November 2026
  7. 74 Active
    Mailcow

    mailcow: dockerized - + =

    GPL-3.0
    Setup
    4 of 5
    Stars
    13.8k
    Release
    5 November 2026
  8. 73 Active
    Maddy Mail Server

    Composable all-in-one mail server.

    GPL-3.0
    Setup
    Docker
    Stars
    6.1k
    Release
    5 November 2026
  9. 71 Active
    Modoboa

    Mail hosting made simple

    ISC
    Setup
    4 of 5
    Stars
    3.5k
    Release
    26 October 2026
  10. 70 Active
    Haraka

    A fast, highly extensible, and event driven SMTP server

    MIT
    Setup
    Docker
    Stars
    5.6k
    Release
    5 November 2026
  11. 61 Active
    SimpleLogin

    The SimpleLogin back-end and web app

    AGPL-3.0 relicensed 2021
    Setup
    Docker
    Stars
    7.1k
    Release
    6 November 2026
  12. 59 Active
    Mox

    modern full-featured open source secure mail server for low-maintenance self-hosted email

    MIT
    Setup
    1 of 5
    Stars
    5.9k
    Release
    19 August 2026
  13. 57 Active
    Stalwart Mail Server

    All-in-one Mail & Collaboration server. Secure, scalable and fluent in every protocol (IMAP, JMAP, SMTP, CalDAV, CardDAV, WebDAV).

    Unidentified license license unclearpaid features in repoCLA
    Setup
    Docker
    Stars
    15.9k
    Release
    9 November 2026
  14. 53 Active
    Mail-in-a-Box

    Mail-in-a-Box helps individuals take back control of their email by defining a one-click, easy-to-deploy SMTP+everything else server: a mail server in a box.

    CC0-1.0
    Setup
    From source
    Stars
    15.5k
    Release
    26 September 2026
  15. 53 Active
    AnonAddy

    Anonymous email forwarding

    AGPL-3.0 relicensed 2022
    Setup
    From source
    Stars
    5k
    Release
    29 October 2026
  16. 46 Active
    iRedMail

    Full-featured, open source mail server solution for mainstream Linux/BSD distributions.

    GPL-3.0
    Setup
    From source
    Stars
    1.9k
    Release
    None
  17. 45 Active
    Postal

    A fully featured open source mail delivery platform for incoming & outgoing e-mail

    MIT
    Setup
    2 of 5
    Stars
    17k
    Release
    3 June 2026

Our picks by use case

  • Mailboxes for your own domains

    docker-mailserver packs Postfix, Dovecot, Rspamd, ClamAV, OpenDKIM and Fail2ban into one container, configured through files you can keep in git.

  • Mail, calendars and contacts in one server

    Stalwart Mail Server speaks SMTP, IMAP, JMAP, CalDAV, CardDAV and WebDAV, and manages accounts, domains and queues in a web interface.

  • Sending email from websites and apps

    Postal delivers transactional and bulk mail for your applications and accepts incoming messages for them, as a self-run replacement for Sendgrid, Mailgun or Postmark.

  • Larger and multi-tenant setups

    Stalwart Mail Server handles multi-tenancy, LDAP or OpenID Connect sign-in, several storage backends and clusters spread over many nodes.

How to choose an email server

Running mail takes more care than most self-hosted services. Whichever server you install, DNS records, certificates and the reputation of your sending IP address become your job, and mistakes show up as messages that never reach an inbox.

Mailboxes or sending only

Postal is built for applications that send and receive mail, not for personal inboxes. docker-mailserver and Stalwart give people real mailboxes that desktop and phone mail apps connect to. Decide by who reads the mail: people or code.

DNS and deliverability

Self-run mail puts SPF, DKIM and DMARC records, TLS certificates and the standing of your sending IP on you. docker-mailserver signs and checks messages with OpenDKIM and OpenDMARC, and Stalwart has DKIM, SPF, DMARC, DANE and MTA-STS built in. Postal leaves IP reputation and deliverability to its operator as well.

Configuration style

docker-mailserver has no web interface and no SQL database: you work with environment variables, configuration files and a setup script. Stalwart manages accounts, domains, queues, reports and logs in the browser. Postal runs in Docker with MySQL as its database.

License and maintainers

docker-mailserver and Postal are MIT-licensed with no paid parts. Stalwart's license could not be identified from the data, some of its features sit under a separate paid licence, and contributors must sign a CLA. Postal saw only three commits in the last 90 days, about 88 percent of recent Stalwart commits come from one developer, and docker-mailserver had 19 contributors.

Drafted with AI from the projects’ READMEs and our data, then checked against that data on 7 November 2026. Report a correction

Which of these are really open source?

Fully open source (16)OSI-approved license, no paid parts in the repository
docker-mailserver, Postal, Mail-in-a-Box, Mailcow, Mailu, Roundcube, SimpleLogin, Maddy Mail Server, Mox, Haraka, AnonAddy, Modoboa, wildduck, iRedMail, Cypht, SnappyMail
Open source with paid parts (0)OSI license, but some features are under commercial terms
None
Not OSI open source (1)Code is public, use is restricted
Stalwart Mail Server (Unidentified license)
License changesNewest first
AnonAddy: MIT → AGPL-3.0, 2022; SnappyMail: MIT → AGPL-3.0, 2022; SimpleLogin: MIT → AGPL-3.0, 2021; Cypht: GPL-2.0 → LGPL, 2020

Read automatically from each repository’s license files every day. How we read licenses

Questions about open-source email servers & webmail

What are the most popular open-source email servers & webmail projects?

By GitHub stars: docker-mailserver (19.7k), Postal (17k), Stalwart Mail Server (15.9k). By our health score, the most actively maintained are Roundcube (86), Cypht (85), docker-mailserver (80).

Which email servers & webmail projects are fully open source?

16 of the 17 use an OSI-approved license with no paid parts in the repository, including docker-mailserver, Postal, Mail-in-a-Box.

Which are the easiest to self-host?

Judged by the services in their compose files, docker-mailserver, Postal, Mailu, Mox need the least setup.

Which projects have changed their license?

SimpleLogin (to AGPL-3.0 in 2021), AnonAddy (to AGPL-3.0 in 2022), Cypht (to LGPL in 2020), SnappyMail (to AGPL-3.0 in 2022). Each project page links to the commit that made the change.

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