20 self-hosted Fastmail alternatives

Production-ready mail server stack in a Docker container with SMTP, IMAP/POP3, LDAP auth, anti-spam/AV, DKIM/DMARC, and optional OAuth2 support.

18.6k stars2k forksMITlast commit 18 Jul 2026Actively maintained

Mail-in-a-Box is a one-click mail server appliance for Ubuntu, bundling SMTP/IMAP, webmail, DNS, TLS automation, backups, and an admin control panel.

15.4k stars1.5k forksCC0-1.0last commit 24 May 2026Actively maintained

All-in-one open-source mail and collaboration server with SMTP, IMAP, JMAP, CalDAV, CardDAV, and WebDAV, plus integrated anti-spam and phishing protection.

13.9k stars848 forkslast commit 27 Jul 2026Actively maintained

Mailcow is a dockerized mail server suite providing SMTP/IMAP, webmail, anti-spam/anti-virus, and domain/mailbox administration via a unified web UI.

13.2k stars1.8k forksGPL-3.0last commit 15 Jul 2026Actively maintained

Mailu is a full-featured mail server distributed as Docker images, providing SMTP/IMAP/POP3, webmail, administration UI, and built-in security and anti-spam features.

7.4k stars990 forkslast commit 26 Jul 2026Actively maintained

Open source webmail client for IMAP with address book, search, folders, and a customizable UI via plugins and skins.

7.1k stars1.8k forkslast commit 25 Jul 2026Actively maintained

Go-based, modular mail server implementing SMTP/LMTP/IMAP with built-in DKIM/SPF/DMARC, storage backends (SQLite/Postgres/S3), Prometheus metrics and Docker support.

6k stars324 forksGPL-3.0last commit 13 Jul 2026Actively maintained

All-in-one secure mail server with SMTP, IMAP, webmail, automatic TLS (ACME), and built-in SPF/DKIM/DMARC plus junk filtering for low-maintenance domains.

5.8k stars210 forksMITlast commit 20 Jul 2026Actively maintained

Modoboa is an open source mail server management platform with a modern web UI, integrating Postfix and Dovecot with admin tools, webmail, calendar, and address book.

3.5k stars476 forksISClast commit 27 Jul 2026Actively maintained

A Bash script that auto-implements a full mail server (Postfix, Dovecot, DKIM, SpamAssassin) with TLS and PAM-based logins on Debian/Ubuntu.

2.2k stars340 forksGPL-3.0last commit 4 May 2025Slowing down

Open source groupware suite providing webmail, calendaring, address books, and shared resources via open standards like IMAP, CalDAV, and CardDAV.

2.1k stars311 forksGPL-2.0last commit 15 Jul 2026Actively maintained

WildDuck is a horizontally scalable IMAP/POP3 mail server that stores all mail in MongoDB, runs stateless Node.js workers, and provides a REST API for full server control.

2.1k stars276 forksEUPL-1.2last commit 27 Jul 2026Actively maintained

Automated open-source mail server installer bundling Postfix, Dovecot, webmail, anti-spam/antivirus and LDAP/SQL backends for mainstream Linux/BSD.

1.8k stars259 forksGPL-3.0last commit 22 Jul 2026Actively maintained

SnappyMail is a fast, modern webmail client (RainLoop fork) focused on performance, privacy, and secure IMAP access with optional PGP support and admin controls.

1.7k stars211 forksAGPL-3.0last commit 11 Mar 2026Actively maintained

High-performance, standards-compliant IMAP/POP3/LMTP server with flexible authentication, extensible plugin system (Lua, Sieve) and OpenSSL TLS support.

1.2k stars345 forkslast commit 24 Jul 2026Actively maintained

Nextcloud Mail is a webmail app that connects to IMAP/SMTP accounts, offering a unified inbox and deep integration with other Nextcloud apps like Contacts and Calendar.

1k stars335 forksAGPL-3.0last commit 28 Jul 2026Actively maintained

Cyrus IMAP is a secure, scalable mail server providing IMAP/JMAP email plus CalDAV/CardDAV contacts and calendars, with ACLs, quotas, search, and replication.

637 stars173 forkslast commit 27 Jul 2026Actively maintained

Open-source PHP groupware providing CalDAV/CardDAV, ActiveSync, email client, CRM, tasks, file manager and Docker images for on-premise collaboration.

21 stars5 forksAGPL-3.0last commit 27 Jul 2026Actively maintained

Courier is an integrated mail server suite providing ESMTP (MTA), IMAP, POP3, webmail, and mailing lists with optional LDAP/MySQL/PostgreSQL-backed virtual accounts.

Activity unknown

Simple NixOS Mailserver provides NixOS modules to deploy a full email server with SMTP/IMAP, spam filtering, DKIM/DMARC/SPF, and TLS automation.

Activity unknown