http://www.howtoforge.com/linux_postfix_virtual_hosting I've followed the above tutorial and got postfix/dovecot with Mailscanner functioning. I however, have one issue, as this will not be used for local mail only (as the configuration in the howto suggest), and need to be able to allow relaying by authenticated users (on infinite public networks). I have sasl working with smtpd, and it will allow me to authenticate with actual unix users (listed in /etc/passwd), but I cannot seem to get it to work with virtual users. I have been able to locate plenty of tutorials showing how to get sasl/smtpd to work with mysql based configurations, but none with the flat file system that this tutorial uses. Can anyone make a suggestion as to what needs to be configured to allow these virtual users to authenticate with smtpd, and how? W.