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

Stefan Neufeind v6ops at
Fri Aug 22 10:09:10 CEST 2014

On 08/22/2014 09:56 AM, Laurent GUERBY wrote:
> We've been running SMTP over IPv6 with postfix successfully for over a
> year and since 20140818 IPv6 MX started to classify most IPv6
> sourced emails sent from our machine to as spam. The exact
> same message sent using IPv4 within one minute of the IPv6 bounce is
> accepted.
> As there's no way to reach google mailops we had to remove IPv6 from our
> mail machines and go back to IPv4 only for mail, which is sad.
> Are we alone with this recent experience?

Those are the symptoms others have experienced before, some not (for
some reason). It's been discussed on several mailinglists. And
unfortunately there was no solution yet. Some people have tried to
contact a personal contact at Google here and there - but afaik with no
success or even feedback so far. Several others resported they went back
to IPv4-only for outbound SMTP (inbound is fine) or applied certain
hacks to only deny IPv6 towards Google.

Kind regards,

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