The pipe.pl script provides a way to have POPFile classify messages piped to it by other processes that can then take the classified message and deal with it.
What it does
Accepts the raw message text (you should include headers) on STDIN
Classifies the message and inserts the POPFile X-Text-Classification and/or performs Subject line modification as configured in POPFile.
Emits the now classified message (including new header and modified Subject line) on STDOUT