Gmail (thus Nanog) rejecting ipv6 email

Sat Apr 2 22:24:42 UTC 2022

* danm at prime.gushi.org (Dan Mahoney (Gushi)) [Sun 03 Apr 2022, 00:11 CEST]:
>I've been seeing a long thread about why ipv6 adoption isn't there  
>yet. This is half a "paging someone with clue" post and half a  
>"...really, guys?" Picard-facepalm post.
>
>I just (earlier this week) had to disable ipv6 outbound on one of  
>$dayjob's MX servers, because Gmail, who hosts nanog.org, was  
>rejecting our mail due to "our domain's very low reputation".  (In  
>this parlance, "Very Low" is an actual indicative metric.) Dayjob is 
>the people who make BIND and run a root DNS server.  Totally  
>disreputable, I'm sure.
>
>I don't see anything indicating this in our postmaster tools.
>
>I am certain this action is happening completely transparently and  
>invisibly to NANOG, unless others have complained.  Whatever UI 
>google gives them to manage their domain will not show this.  There 
>are no logs they can grep.
>
>I'm told that "gmail's filters for ipv6 are way tighter than ipv4" 
>but that's from a non-canonical source.  If this is the case, it 
>does very little to further ipv6 adoption, that's for sure.
>
>I've posted over on mailop, and was given a contact (Brandon), but  
>haven't heard back.  Gmail's a black box.  I've reached out to a few 
>other people, but if anyone here can loan a bat-phone, please let me 
>know.
>
>I'm loathe to randomly re-enable ipv6 without contact from someone  
>saying why this happened, and how it's been fixed.
>
>-Dan
>(Who actually operates my own network)

I also run my own mail server. I had to firewall off Google's MXes for 
this exact reason: silent and not-so-silent email rejection when 
offered over IPv6.

Every now and then they rotate their IP addresses, which causes mail 
to get dropped for a while.

There is no other conclusion possible than that Gmail is actively 
anti-email at this point. I'm pretty sure I receive more spam from 
them than I send to them, despite forwarding all emails for a few 
family members' domains.

	-- Niels.