[Exim] RBL feature request

As we (those in .ac.uk) are being pushed into using rbl-plus, I'd like to
know which of the RBL, DUL & RSS list my RBL+ mails. Unfortunately, at
present Exim will not record the returned IP address in the X-RBL-Warning:
header, so everything is listed as "(rbl-plus...)".

I (and I guess other JANET Exim postmasters) would like to see this in
Exim 3, (would it be easier in Exim 4 anyway?) and from a quick look at
the source it doesn't look too difficult, but I'm scared to do it myself
as (a) I'm not a brilliant programmer and (b) I know nothing of IPv6.

Sorry to wish this on the day of an Exim release!

Matt