header checks not working

[Rob Brandt]

I'm trying to set up a basic header check to get rid of emails sa marks 
as spam.  I've added the following link to main.cf:

header_checks = regexp:/etc/postfix/filter
/etc/postfix/filter has:


# No ***SPAM***
/^Subject .*\*\*\*SPAM\*\*\*/   DISCARD ***SPAM***
# SPam flag
/^X-Spam-Flag .YES/     DISCARD Spam Flag

The intent is to discard emails where either the subject contains 
***SPAM*** or the X-Spam-Flag is YES

But the filters aren't working.  I am by no means a regex expert.  What 
am I missing?

Rob