is gmail strongly penalizing IPv6 senders?

[Marco d'Itri]

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.)

-- 
ciao,
Marco
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