This is version 2 of the Perl filter enhancement patch, ported to INN 2.0. Apply this patch in the nnrpd directory of the source tree.
Affected files are perl.c and post.c.
Obviously this has no effect unless you use authinfo. Adds a returncode DROP to the Perl interface. If the string returned by the Perl subroutine begins with DROP, the post will be discarded and success returned to the client. They can be injected manually with rnews. This is somewhat inconvenient.