5 Nov
2015
5 Nov
'15
3:15 p.m.
There is still the small issue of the fact that www.mailmanlists.us doesn't have a AAAA record or a ipv6 ptr record defined. This also has the potential to help get stuff caught up in spam filters, but that is something they need to fix on their end.
You may also need to specify a prefix, rather than a single address, for the IPv6 SPF record. Depends on if they really only have one outgoing server in the middle of an IPv6 subnet, or if there are in fact multiple machines there on different addresses and we've only seen the one so far. Thanks, Jonathan