<div dir="ltr">On Mon, Sep 2, 2013 at 10:05 AM, Jason Fesler <span dir="ltr"><<a href="mailto:jfesler@gigo.com" target="_blank">jfesler@gigo.com</a>></span> wrote:<br><div class="gmail_extra"><div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">On Sun, Sep 1, 2013 at 5:30 PM, Lorenzo Colitti <<a href="mailto:lorenzo@google.com">lorenzo@google.com</a>> wrote:<br>
> What's wrong with wildcard PTRs?<br>
><br>
> *.e.f.a.c.8.b.d.0.1.0.0.2 IN PTR <a href="http://customer-cafe.isp.net" target="_blank">customer-cafe.isp.net</a>.<br>
<br>
</div>And, <a href="http://xn--customer-caf-meb.isp.net" target="_blank">customer-café.isp.net</a> has AAAA records to what exactly?<br>
<br>
It isn't just reverse DNS. It is reverse + matching forward DNS.<br>
Mismatches in the IPv4 world are greatly penalized both at SMTP time<br>
and by SpamAssassin.<br></blockquote><div><br></div><div>To 2001:db8:cafe::. Then we can modify SMTP servers and spam systems to look at only the first 64 bits and we sort of have parity to what we have today.</div><div>
<br></div><div>Of course, if people put multiple customers on the same /64 then those customers can influence each other's reputations. But this is no different to what happens today to customers on the same public IPv4 address (e.g., shared hosting, SMTP relay).</div>
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