I have a client that runs a program called DMPro. This is a multi-autoresponder that sends up to ten autoresponses to the recipient. This could be used as a sales followup or a training series or many other applications.
The program uses a .forward file to read all incoming mail looking for mail addressed to one of the autoresponders. If it detects one it forwards that piece of mail onto a cgi program who handles the rest of that process. It may be an enrollment or someone wanting to be removed.
Anyhoo, I was over at the Exim website looking through the documentaion and Exim can use .forward files but I am confused as to where I can place that file.