[exim] Logging ACL denies

In my ACLs I have this:

  deny
    message = sender IP $sender_host_address is blacklisted (in $host_data)
    !acl = acl_whitelist_local_deny
    hosts = ${if exists{CONFDIR/local_host_blacklist}\
                 {CONFDIR/local_host_blacklist}\
                 {}}

It works, except that the (in $host_data) bit is interpolating nothing
for the variable. I've obviously got the wrong variablename, which one
should I be using?

--
David Cantrell | London Perl Mongers Deputy Chief Heretic

Graecum est; non legitur