Apps similar to Stalwart include mailcow: dockerized, which is free and open source. Other options are Postfix, Mail-in-a-box, Mailu and WildDuck. In total there are seven Mail Servers like Stalwart for self-hosting, Linux and Mac.
mailcow is a mail server suite based on Dovecot, Postfix, SOGo, Rspamd and other open source software, that provides a modern Web UI for administration.
Germany
EU
Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail. It attempts to be fast, easy to administer, and secure. The software is also known by its former names VMailer and IBM Secure Mailer.
United States
Mailu is a simple yet full-featured mail server as a set of Docker images. It is free software (both as in free beer and as in free speech), open to suggestions and external contributions.
WildDuck is a scalable no-SPOF IMAP/POP3 mail server. WildDuck uses a distributed database (sharded + replicated MongoDB) as a backend for storing all data, including emails.
Mox is a modern full-featured open source secure mail server for low-maintenance self-hosted email.
Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container.
