If you noticed a recent spike in your Gmail open rates from mails sent through BulkResponse then you are not alone.
We have been quietly testing IPV6 implementation for a select few customers over past few months, and we are glad to announce that now we are rolling out this feature to all our BulkResponse users gradually.
We are currently allocating 100 IPV6 IPs per user (we can actually do 1000, but we are just trying to be conservative). That is out of 1 trillion IPs we received from our data center on a single server . If you like math, exact number would be 2128 IPs per server. That is just over 1 billion IPs :)
Currently Only Gmail supports IPV6
Bad news is that currently only ISP that accepts IPV6 mails is GMail. What that means is, when we try to send mail to other ISPs using IPV6, we get connection timeout , which means they dont have any valid IPV6 MX records published.
While all ISPs really encourage IPV6 regime, they are little behind MR. Google in actually implementing it. GMail is ONLY isp currently accepting IPV6 mails.
This also means that your mails will continue to be routed through old IPV4 IPs for other ISPs like Yahoo, aol and hotmail. We hope these ISPs will follow Google soon and implement IPV6, so that we can assign more IPs per user , which ultimately will mean better email deliverability for our clients.
Read More About IPV6 Here: http://en.wikipedia.org/wiki/IPV6