Re: rDNS and cache issues, was How will we manage IPv6 spam?

>For the case of abusive behaviour (ie, spammer using vast pools of IP
>addresses, eg > 10^3 IP addresses, either snowshoe-like or in cannon
>style), DNS caches will only blow if receiving systems are "dumb", ie
>do not handle dDoS-like patterns appropriately. That's already an
>issue today, and will only be "somewhat worse" in an IPv6 world.

How can an MTA tell whether a connection from a hitherto unseen IP
is part of a DDoS or a real user sending mail for the first time?

R's,
John