Hi
The same 'bug' (more a difference in convention, really) seems to exist in SPF checks.
So (v6.0)...

65.125.54.126 in an SPF record in DNS will be checked against ::ffff:65.125.54.126 and fail

...potentially leading to message rejection rather than just a bit of extra spam (as in the RBL check
problem). Not necessarily yet a priority, of course, and great to see any kind of support for IPv6!
Regards
Andrew