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

[Lyle Giese]

If the provider won't or is unable to provide reverse for the IPv6 
static address you have, it will be sub-optimal for you to continue to 
advertise and/or use the IPv6 address for SMTP.

It's all part of the 'prove it's not a dynamic ip address' and part of 
the 'proper reverse DNS provides some level of authority/delegation to 
use that ip address for legit SMTP usage'.

Lyle Giese
LCR Computer Services, Inc.


On 11/02/14 14:38, Matija Grabnar wrote:
> On 11/02/2014 06:55 PM, Darren Pilgrim wrote:
>> On 8/22/2014 2:46 AM, Matija Grabnar wrote:
>>> So, much as I would LIKE to have reverse IPv6 DNS on my mail 
>>> servers, in
>>> some cases it is just not possible.
>>
>> Can you describe those cases?  I can't think of any scenarios where 
>> you'd run a correctly-configured public MX and not have reverse DNS.
> Bah - I have a correctly configured public MX on my home network 
> (static IPv4, static IPv6). It's correctly configured, but I have been 
> as of now unable to convince my provider to delegate reverse DNS (for 
> IPv6) to my DNS. They are simply not set up for that. Otherwise, the 
> MX is completely correctly configured. Under IPv4 it even has a PTR 
> (for the lone static IPv4 address).
>
> And I've had similar problems ("we are not set up to delegate reverse 
> DNS for IPV6") with a hosting provider. I had a suggestion on the list 
> that I should simply rehost my machines, but alas it is not practical, 
> since the provider was chosen for a bunch of other parameters 
> (bandwidth cost, hosting cost, etc), with IPv6 connectivity an 
> afterthought.
>
> It is completely possible to have a "correctly configured public MX" 
> and not have a reverse DNS - unless your definition of "correctly 
> configured public MX" demands a reverse DNS, but I assume you wouldn't 
> insult both our intelligences with a "no true scotsman" fallacy of 
> that sort.