Question : Exim mail server on Fedora with WHM

We have a mail server (85.118.232.134) as part of a WHM setup which is hosting many websites.

I have done a relay test on mailradar.com all of which fail but im not quite sure why.  Is anyone able to make some suggestions as to how i can make sure this server isnt being used for any form of open relaying?

Answer : Exim mail server on Fedora with WHM

If it is spam related it is in the spamassassin configuration: (this is from my amavisd config file).
%final_destiny_by_ccat = (
  CC_VIRUS,      D_DISCARD,
  CC_BANNED,     D_DISCARD,
  CC_UNCHECKED,  D_PASS,
  CC_SPAM,       D_DISCARD,
  CC_BADH,       D_PASS,
  CC_OVERSIZED,  D_BOUNCE,
  CC_CLEAN,      D_PASS,
  CC_CATCHALL,   D_PASS,
);
So it's handled in a wrapper around spamassassin with mine.
I only bounce oversized to warn the sender, the others are either discarded or passed on.