we need the relevant maillog transaction for your email rejection, do you use a POP3 Proxy for them ?
one way to test the spam rejection is the string below in an email
XJS*C4JDBQADN1.NSBN3*2IDNEN*GTUBE-STANDARD-ANTI-UBE-TEST-EMAIL*C.34X
if you want to test the antivirus send a test attachment that you can find at http://securite-informatique.info/virus/eicar/
search for eicar if you don’t understand french