[Exim] system filter fail option

I have a small system filter which examines $header_subject and $message_body
for some specific SPAM identifiers and if TRUE, fails the delivery
as shown in the example under 47.2 in TFM.

    then fail text "spam is not wanted here" endif

It appears that this creates an email BACK to the originator, rather than
just FAILing the SMTP session. I've had a FAIL message come back to *me*
because the 'recipient' was unknown.

How do you fail a message so that the SMTP session get's refused? Or what
am I missing?
--
Jim Pazarena    mailto:paz@qcislands.net
                http://www.qcislands.net/paz