/etc/courier/module.fax is in courier-mta 0.73.1-1.6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6
NAME=fax PRIORITY=45 PROG=./courierfax MAXDELS=1 MAXHOST=1 MAXRCPT=1