Software

Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container. Only configuration files, no SQL database. ([Source Code](https://github.com/docker-mailserver/docker-mailserver))

SMTP server that sends and receives emails according to a simple configuration file, with an optional web interface that you can use to browse your emails. ([Source Code](https://dovel.email/server/tree.html))

Lets you have an infinite number of unique inboxes. ([Source Code](https://codeberg.org/Inboxen/Inboxen))

Full-featured mail server solution based on Postfix and Dovecot. ([Source Code](https://github.com/iredmail/iRedMail))

All-in-one mail server that implements SMTP (both MTA and MX) and IMAP. Replaces Postfix, Dovecot, OpenDKIM, OpenSPF, OpenDMARC with single daemon. ([Source Code](https://github.com/foxcpp/maddy))

Turns any Ubuntu server into a fully functional mail server with one command. ([Source Code](https://github.com/mail-in-a-box/mailinabox))

Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration. ([Source Code](https://github.com/mailcow/mailcow-dockerized))

Simple yet full-featured mail server as a set of Docker images. ([Source Code](https://github.com/Mailu/Mailu))

Mail hosting and management platform including a modern and simplified web user interface. ([Source Code](https://github.com/modoboa/modoboa))

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 Let's Encrypt, account autoconfiguration, and webmail. ([Source Code](https://github.com/mjl-/mox))

Complete and fully featured mail server for use by websites & web servers. ([Source Code](https://github.com/postalserver/postal))

Complete mailserver solution leveraging the Nix Ecosystem

Open source email alias solution to protect your email address. Comes with browser extensions and mobile apps. ([Source Code](https://github.com/simple-login/app))

All-in-one mail server with JMAP, IMAP4, and SMTP support and a wide range of modern features. ([Source Code](https://github.com/stalwartlabs/stalwart))

Scalable no-SPOF IMAP/POP3 mail server. ([Source Code](https://github.com/zone-eu/wildduck))

Email (IMAP/POP3), contacts and calendar server. ([Source Code](https://github.com/cyrusimap/cyrus-imapd))

IMAP and POP3 server written primarily with security in mind. ([Source Code](https://github.com/dovecot/core))

SMTP (email) server with a focus on simplicity, security, and ease of operation. ([Source Code](https://blitiri.com.ar/git/r/chasquid/))

Fast, scalable, enterprise mail/groupware server providing ESMTP, IMAP, POP3, webmail, mailing list, basic web-based calendaring and scheduling services. ([Source Code](https://www.courier-mta.org/repo.html))

A small and easy to configure SMTP and POP3 server for Windows and Linux. ([Source Code](https://sourceforge.net/p/emailrelay/code/HEAD/tree/))

Message transfer agent (MTA) developed at the University of Cambridge. ([Source Code](https://git.exim.org/exim.git))

Fast, highly extensible, and event driven SMTP server. ([Source Code](https://github.com/haraka/Haraka))

Secure SMTP server implementation from the OpenBSD project. ([Source Code](https://github.com/OpenSMTPD/OpenSMTPD/))

Fast, easy to administer, and secure Sendmail replacement