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

[Brian E Carpenter]

On 23/08/2014 11:16, 🔓Dan Wing wrote:
> On Aug 22, 2014, at 7:42 AM, Matthew Huff <mhuff at ox.com> wrote:
> 
>> 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.
> 
> MTU issue?

I can't speak for Teredo, but for 6to4 there is a whole list of
possible issues ( http://tools.ietf.org/html/rfc6343 ). PMTUD failure
and/or MSS negotiation failure are on the list, and so is reverse
DNS failure.

   Brian

> 
> -d
> 
> 
>> 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.
>>
>>
>>
>> ----
>> 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
>>
> 
>