The qmail Handbook

Sendmail uses .forward files to allow users to control the delivery of messages they receive. qmail uses a similar mechanism: .qmail files. The dot-forward package gives qmail the ability to use .forward files. Systems running Sendmail or any other MTA that uses .forward files might want to consider using dot-forward to avoid having to convert existing .forward files to their .qmail equivalents—or simply to make the transition to qmail less visible to their users.

dot-forward is a small package, so it's easy to install and configure. Chapter 7, "qmail Configuration: Advanced Options," covers installing and configuring dot-forward.

dot-forward was written by Daniel Bernstein, who maintains a Web page for it (http://cr.yp.to/dor-forward.html).