Gmail (thus Nanog) rejecting ipv6 email

Sun Apr 3 01:37:43 UTC 2022

On 4/2/22 6:16 PM, John Levine wrote:
> It appears that Michael Thomas <mike at mtcc.com> said:
>>> 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
>>>    - SPF
>>>    - DKIM
>>>    - DMARC
> Yup.  Gmail has made it quite clear that they will not accept v6 mail that
> isn't SPF or DKIM authenticated.  DKIM is more work but works more reliably.
>
>>>    - ARC (for mailinglists)
>> Seriously spend zero time on ARC. It doesn't work as advertised ...
> Please, not this again. ARC does what it does, even if it doesn't do
> what you might wish it did instead.

I does what it does which is DKIM. That's it.

> It's certainly not a magic ticket into an inbox but it is slowly
> helping undo DMARC mailing list damage.  It's not important unless
> you forward mail like a mailing list does.

No it doesn't. It requires the previously unsolved problem of reputation 
which manifestly incapable of being solved. DMARC is not the problem, 
ancient mailing list technology which came before security requirements 
is the problem.

Mike