This guide focuses on making Yaa! (Yet Another Autoresponder!) work with Debian Sarge and the virtual users on Postfix tutorial
Read it here
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!