[exim] detect, if malware scanner is unreachable

hi,

   it is possible to "mark" spam emails, in case spamassassin is not
   reachable:
     warn       spam = nobody/defer_ok
          add_header = X-Spam-Flag: YES
     warn  condition = ${if !def:spam_score_int {1}}
          add_header = X-Spam-Note: Spamcheck invocation failed
          add_header = X-Spam-Status: Unknown

     warn  condition = ${if def:spam_score_int {1}}
           condition = ${if <{$spam_score_int}{50} {1}{0}}
          add_header = X-Spam-Status: No, score=$spam_score

     warn  condition = ${if def:spam_score_int {1}}
           condition = ${if >={$spam_score_int}{50} {1}{0}}
          add_header = X-Spam-Status: Yes, score=$spam_score

is sthg like this possible with the malware scanner(s)?

   it is clear that
     deny    malware = */defer_ok
             message = This message contains a malware or virus
   ($malware_name).
         log_message = $sender_host_address tried sending $malware_name
   rejects the email immediatelly and a X-Malware-Status: Yes is
   irrelevant.

   but it would still be nice to have either
      X-Malware-Status: Unknown
   or
      X-Malware-Status: No
   in the email header.

hope i was clear enough, as i am quite new to exim.

thank you in advance, niki