Re: Gmail (thus Nanog) rejecting ipv6 email

[Michael Thomas <mike () mtcc com>]

On 4/2/22 3:56 PM, Jeroen Massar wrote:
> > On 3 Apr 2022, at 00:29, Michael Thomas <mike () mtcc com> wrote:
> >
> >
> > On 4/2/22 3:23 PM, Jeroen Massar via NANOG wrote:
> > > Hi Dan,
> > >
> > > Hope the rest of the world is treating you decently!
> > >
> > > There are a lot of bits and bobs that one has to get right for mail to flow, amongst which:
> > >
> > >   - IP -> PTR lookup -> that hostname lookup, and match to IP again
> > >     (https://en.wikipedia.org/wiki/Forward-confirmed_reverse_DNS)
> > >   - SPF
> > >   - DKIM
> > >   - DMARC
> > >   - ARC (for mailinglists)
> > Seriously spend zero time on ARC. It doesn't work as advertised... [snip, see below]
> Unless one works at the large ESPs, hard to tell what they really care about and verify.
>
> Google at least adds ARC headers in Gmail, and did the editing of RFC8617.

ARC resolves into a previously unsolved problem: reputation. You could 
do reputation with plain old DKIM too, so I don't see why changing the 
name of the header changes anything on the ground. And nobody could give 
me an answer of why signing previous Authentication-Results is useful 
for toward that end. It's just more magical thinking.

Thank goodness it's an experimental RFC so it can go the way of the dodo.

Mike