refused relay problems?

I've noticed a number of these:
---------------
1997-03-20 02:40:01 refused relay (sender) to
owner-nt-list@??? from <> H=hyperion.cmc.comsat.com
[134.133.173.170]
---------------

Here's my relay setup:

--------------
# anti-abuse
sender_host_accept_relay = *.comsat.com
# ensure that all outgoing relays have legit sender
sender_address_relay = *comsat.com
--------------

So why was this refused?

Would we see different messages to differentiate the
sender_host_accept_relay rule vs. the sender_address_relay rule?