[Exim] Failed condition expansion

(I hope line breakage doesn't make this message entirely unreadable.)

From time to time I find some strange lines in my log files:

2004-05-06 08:15:52 1BLcAe-0006FQ-Ns failed to expand condition \
[...] for spamcheck_router router: "194.248.10.11
127.0.0.1" is not an IP address

I've snipped the actual condition, since it should be easier to
read in its original formatting below. But note the two IP
addresses with a newline between them. Is that a very strange
$sender_host_address, or do I have some error in my condition?
Or could it be X-NR-Originating-IP that contains two addresses?
That header is added like this:

mailman_router:
driver = accept
headers_add = X-NR-Originating-IP: $sender_host_address
[...]

The condition looks like this:

  condition = "${if and { \
         {!def:h_X-NR-SpamProbe:} \
         {!eq {$received_protocol}{spam-scanned}} \
         {!eq {$sender_host_address}{}} \
         {!eq {${mask:$sender_host_address/16}}{156.116.0.0/16}} \
         {or { \
               {and { \
                        {eq {${mask:$sender_host_address/32}}{127.0.0.1/32}} \
                        {and { \
                               {def:header_X-NR-Originating-IP:} \
                               {!eq {$header_X-NR-Originating-IP:}{}} \
                               {!eq {${mask:$header_X-NR-Originating-IP:/16}}{156.116.0.0/16}} \
                             } \
                        } \
                      } \
               } \
               {!eq {${mask:$sender_host_address/32}}{127.0.0.1/32}} \
             } \
         } \
         {< {$message_size}{500000}} \
       } \
  {1}{0}}"

Thanks for any help.

--
Regards,
Stian Grytøyr