is gmail strongly penalizing IPv6 senders?

[Olivier MJ Crepin-Leblond]

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I don't know if it does - I've found our servers appear to have no problem.

Gmail uses a number of things like SPF etc. to define if something's
Spam. Did you check that this designates the IPv6 address as a permitted
sender? Do your SMTP servers have reverse IPv6 addresses? Do you use
DKIM? Just a few suggestions...

Kind regards,

Olivier

On 30/05/2013 16:46, Marco d'Itri wrote:
> I have noticed in the last few days that mail sent to gmail from a
> significant number of our servers (both shared hosting / mail relays and
> dedicated servers of our customers) with IPv6 connectivity is delivered
> to the spam folder.
> If there has been spamming activity (as a result of some security
> incident, I am not an ESP) from some of these servers then it is not
> recent.
> The reputation problem is tied to the IP address, because after adding
> a new one in the same /64 mail is delivered to the inbox.
>
>
> (OTOH, recently I have received significant complaints from customers
> about gmail rejecting connections or delivering to the spam folder even
> long after a security incident, so this may be not specific to IPv6.)
>

- -- 
Olivier MJ Crépin-Leblond, PhD
http://www.gih.com/ocl.html
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