Help w/fist time setup please

[Jim_Marnell]

Spamassassin is not catching most spam. A few emails are caught but most 
are getting through. I've read & investigated all that I could. I need 
help figuring why it's not working 
I'm basically using out-of-the-box spamassassin with no modifications.
spamassassin 2.63
mimedefang 2.41
sendmail 8.12.10
red hat 8 kernel 2.4.20-28.8
 
Any clues what to look at? I appreciate any help rec'd.
jim