Postfix with dkfilter (DomainKeys Implementation)

DomainKeys is an anti-spam software application in development at Yahoo that uses a form of public key cryptography to authenticate the sender's domain. dkfilter is an SMTP-proxy designed for Postfix. It implements DomainKeys message signing and verification. It comprises two separate filters, an "outbound" filter for signing outgoing email on port 587, and an "inbound" filter for verifying signatures of incoming email on port 25. This document is to describe step by step how to install dkfilter for postfix to deploy domainkeys signing and verification.

Autoresponders to accompany Virtual Users and Domains with Postfix, Courier and MySQL

This guide focuses on making Yaa! (Yet Another Autoresponder!) work with Debian Sarge and the virtual users on Postfix tutorial (see http://www.howtoforge.com/virtual_postfix_mysql_quota_courier). The first thing to understand about the guide is that it uses the Virtual  Delivery Agent (VDA) and as a result any of the auto responders that you could use by passing them to a pipe via a .forward file simply won't work as the VDA does not support .forward expansions.  This limitation can be overcome via Procmail/Maildrop delivery but that is messy and slower especially for mail systems that are heavily used.  The simple answer is Yaa!