Today Erwin Hoffmann has released his ucspi-tcp6 v. 0.99. The current version includes an hack by Manvendra Bhangui from indimail.org
which gets tcpserver and qmail's spfcheck to be IPv4-mapped IPv6
addresses compliant, provided that you use his fix to the qmail-spf
patch (my combined patch already has this adjustment to spf).
those interested, a few days ago Manvendra Bhangui
released a package of patches including now not only DKIM and SURBL but also substancial modifications which get SPF and the entire qmail totally IPv6 compliant. The upgrade for me is not so
straightforward, but I'm planning to have it in my big patch soon or
later. For the moment you can play with it downloading from http://sourceforge.net/projects/indimail/files/netqmail-addons/qmail-dkim-1.0/