Tagged spam not deleted

[Bob Morse]

I have been seeing spam which is properly tagged as spam or definitely 
spam get delivered to an address even though that domain has both low 
and high scoring spam set to delete. This seems to happen when the spam 
is sent to a list of email addresses all in the CC field. They are all 
addresses in our hosting system, but many of the domains in the listed 
in the CC field do not have MailScanner configured to delete low and/or 
high scoring spam. I am assuming this is why it's being delivered to one 
of my addresses/domains. Is this correct? If so, is there a way to 
configure it so that it's deleted even though other domains in the CC 
field are not set that way?

Or, is there another possible explanation?

Thanks!