[Exim] Any way to turn off dnsbl lookups for IPV6 addresses?

The dnsbl I am querying doesn't have any v6 addresses in it, and won't
support v6 lookups against it without a patch (it runs rbldns, from the
djbdns suite).

So, I get timeouts whenever a IPv6 IP connects to my server to deliver
mail ...

> 2003-08-17 16:08:36 DNS list lookup defer (probably timeout) for 6.9.d.4.e.1.e.f.f.f.8.f.0.0.2.0.e.0.0.0.3.0.0.0.8.f.4.0.1.0.0.2.rbl.example.com: assumed not in list

So, is there any way to tell exim not to lookup the address against any
dnsbl if the connecting IP is an IPv6 IP?

regards
--srs