This document describes how to install a mail server with Postfix that is based on virtual users and domains, i.e. users and domains that are in a MySQL database. I will also demonstrate the installation and configuration of Courier (Courier-POP3, Courier-IMAP), so that Courier can authenticate against the same MySQL database Postfix uses. In addition to that, this tutorial covers the installation of Amavisd, SpamAssassin and ClamAV so that emails will be scanned for spam and viruses.