[Exim] local domains

Hi,

Does Exim have a concept of "local domains" in a system filter file? I'm
writing a filter to flag certain emails, but only incoming ones. I have
Exim doing virtual hosting and have captured those domains using the line

${lookup{$sender_address_domain}dbm{/etc/exim/domains.dbm}{found}{notfound}}
is "notfound"

But I have some domains that are less virtual and exist in the exim
configuration file with the "local_domains" parameter. Right now I have
each of these hardcoded, but I'm looking for a more portable method to
determine "local" so I can share the file with other Exim hosts I have.

Thanks,
Christopher