Find the HOWTO or step-by-step guide that you need right here.
This HOWTO, from Howtoforge.com provides a great look into how to leverage the best defense against spam on your mail server. Great overview with setp by step instructions: This document describes how to integrate ASSP (Anti-Spam SMTP Proxy) with embedded ClamAV into a mail server based on Postfix featuring virtual users and domains, i.e. users and domains that are in a MySQL database.
HOWTOForge is a great place to pick up some great guides on setting up your server. Here: This guide describes how to set up a full email solution in Debian Linux (all code is from Debian Etch). I was asked to design a secure, scalable, portable solution for a small company. He goes through every stage, from soup to nuts, of all the issues and steps involved in getting your mail up to the level you want it at.
This document explains how to set up secure POP connections using ssh.
