maildirproc is a program that processes one or several existing mail boxes in the maildir format. It is primarily focused on mail sorting, which means moving, copying, forwarding, and deleting mail according to a set of rules. It can be seen as an alternative to procmail, but instead of being a delivery agent (which wants to be part of the delivery chain), maildirproc only processes mail which has already been delivered. That is a feature, not a bug.
