Foghorn is an extensibly DNS proxy and recursive resolver. The plugins are where the magic happens, replace pihole, add your /etc/hosts to your network dns, serve zone files, run as a dev server which returns fuzzed responses and other errors. UDP/TCP/DoT/DoH upstream and down. DNSSEC Support. Bend DNS to your will!

qmail fork with IPV6, TLS, DANE, DKIM, SRS2, SPF, daemontools, qmailanalog, mess822, & ucspi-tcp

The Mailismus mailserver - SMTP, IMAP, POP3, SSL

Web interface for SQLgrey built on Laravel 5

List of "big mailers" for OpenBSD's 'smtpctl spf walk' mechanism

gld, a lightweight greylist daemon for postfix

Greylisting of suspicious source (exported from code.google.com/p/gross)

Postfix policy application written in Go

dynamic and optionally distributed greylisting daemon

OpenSMTPd filter for quick and dirty greylisting

Verify email(s) using correct SMTP conversations (HELO / MAIL FROM /RCPT TO)

A tool to kep the Unifi Country Blocklist Updated

Haraka plugin that implements greylisting