Mox is a modern full-featured open source secure mail server for low-maintenance self-hosted email. Quick and easy to start/maintain mail server, for your own domain(s). SMTP (with extensions) for receiving, submitting and delivering email. IMAP4 (with extensions) for giving email clients access to email. Webmail for reading/sending email from the browser. SPF/DKIM/DMARC for authenticating messages/delivery. Reputation tracking, learning (per user) host-, domain- and sender address-based reputation from (Non-)Junk email classification. Bayesian spam filtering that learns (per user) from (Non-)Junk email. Rejected emails are stored in a mailbox called Rejects for a short period, helping with misclassified legitimate synchronous signup/login/transactional emails. Automatic TLS with ACME, for use with Let's Encrypt and other CA's. DANE and MTA-STS for inbound and outbound delivery over SMTP with STARTTLS, including REQUIRETLS and with incoming/outgoing TLSRPT reporting. Web admin interface that helps you set up your domains and accounts (instructions to create DNS records, configure SPF/DKIM/DMARC/TLSRPT/MTA-STS), for status information, managing accounts/domains, and modifying the configuration file. Account autodiscovery (with SRV records, Microsoft-style, Thunderbird-style, and Apple device management profiles) for easy account setup (though client support is limited). "mox localserve" subcommand for running mox locally for email-related testing/developing, including pedantic mode. Most non-server Go packages mox consists of are written to be reusable.
At least it tells you how to compile and install it so you don't have to reverse engineer a bunch of Dockerfiles.