[exim] System Filter problem

I have a system filter that has a rule that looks like this:

if ${lc:$h_To:} matches "^rt@???"
or ${lc:$h_To:} matches "^<rt@???>" and
         (
         $sender_address_domain does not contain "domain.com"
         )
then
         fail text "Email to our request tracker system MUST come from a 
  Company address."
endif

This seems to be blocking ALL mail to rt@??? though and I cannot
figure out what I have done wrong. Basically i want to stop anyone from
sending to rt@??? unless their from address contains domain.com.

Gary