Hi I noted that postfix is writing headers with "unknown" instead of the IPv6 reverse DNS that I know exists.
e.g. Received: from merboo.mamista.net (unknown [IPv6:2001:470:1f0b:1055::1]) by tigger.mamista.net (Postfix) with ESMTP id 581F21100B4 for <sage...@sage-au.org.au>; Mon, 22 Mar 2010 02:18:00 +1100 (EST) $ dig -x 2001:470:1f0b:1055::1 +short merboo.mamista.net. I'm still convinced the problem is not with postfix but is there a way to imitate it's IPv6 reverse DNS lookups so I can get closer to the cause of the problem? cheers Marty