SMTP over IPv6 : gmail classifying nearly all IPv6 mail as spam since 20140818

[Matthew Huff]

Currently it is not feasible to do ipv6 reputation filtering. IPv4 reputation filtering is a big part of most anti-spam engines, so without it, SPF / DKIM of domain reputation is the best alternative.

BTW, we have had to remove all IPv6 from our mail gateways due to the large number of Exchange SBS with broken isatap/6to4 tunnels causing mail to blackhole. These have been at small web based retailers which don't have hosted email. After the third incident, we yanked our IPv6 from our MX/gateways.



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Matthew Huff             | 1 Manhattanville Rd
Director of Operations   | Purchase, NY 10577
OTA Management LLC       | Phone: 914-460-4039

-----Original Message-----
From: ipv6-ops-bounces+mhuff=ox.com at lists.cluenet.de [mailto:ipv6-ops-bounces+mhuff=ox.com at lists.cluenet.de] On Behalf Of Nick Hilliard
Sent: Friday, August 22, 2014 10:25 AM
To: Lorenzo Colitti; Laurent GUERBY
Cc: IPv6 Ops list
Subject: Re: SMTP over IPv6 : gmail classifying nearly all IPv6 mail as spam since 20140818

On 22/08/2014 15:16, Lorenzo Colitti wrote:
> Are you following the "Additional guidelines for IPv6" section of
> https://support.google.com/mail/answer/81126 ?

Lorenzo,

it looks like Google is trying to enforce SPF / DKIM on ipv6 connections 
where there is no similar requirement for ipv4.  Is there a particular 
reason for this?  It's causing a lot of breakage.

Nick