Maddy

Maddy is a mail server written in Go. It sends and accepts mail over SMTP, stores messages for IMAP access, and implements DKIM, SPF, DMARC, DANE and MTA-STS in one daemon. The setup tutorial describes the pre-built tarball, which includes a systemd unit, and the Docker page describes the official image. The FAQ compares it with MailCow and Mail-in-a-Box, which bundle other software, where Maddy is one program.

Its own pages show mail submitted to the Submission endpoint by Mailman 3, a mailing list manager, with authentication and TLS. SQLite and PostgreSQL hold the mail index, and LDAP can verify passwords.

Worth knowing

The README calls IMAP storage beta. The project has no admin web interface and no webmail; the FAQ says administration is done with the command-line utility.