Debian Tutorials posted a tutorial about configuring the goldfish autoresponder for Postfix

goldfish is a quite simple autoresponder for Postfix in conjunction with MySQL, written in PHP. It consists of only one PHP file which can be started through a cronjob.
In this tutorial, it's assumed that you have already installed Postfix with MySql backend using this tutorial: Installing Postfix with MySql backend and SASL for SMTP [...]

  Configuring goldfish autoresponder for Postfix