Re: [Asrg] [ASRG] SMTP pull anyone?

Graeme Fowler <> Wed, 26 August 2009 22:17 UTC

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Subject: Re: [Asrg] [ASRG] SMTP pull anyone?
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Apologies if this comes over in an inflammatory or tediously weak way,

On Wed, 2009-08-26 at 17:22 -0400, Daniel Feenberg wrote:
> I understand that many IPv6 capable MTAs exist, but I expect they do all 
> or nearly all of their external traffic via IPv4. I don't mean a general 
> condemdantion of IPv6, I am only saying that SMTP traffic from strangers 
> on IPv6 is not likely to be worthwhile.

This is different from IPv4 SMTP traffic from strangers how, exactly?
The vast majority of previously unseen connections handled by MTAs under
my direct control right now using v4 only are "not likely to be
worthwhile". The fact that there are several powers of 2 (well, many)
more hosts in the v6 world makes no difference apart from a scaling

Imagine if I ran a hypothetical organisation which used network
intelligence gathered from previous SMTP sessions to determine how to
handle a connection from a previously unseen host - it wouldn't matter a
jot if those connections came from a v4 or a v6 host. The only common
factor is that they were previously unseen (ie a "stranger").

Well run organisations will fix the address (as they do now) of their
outbound MTAs, and therefore allow intelligence to build up over time
about their usage and "goodness quotient". If anyone's crazy enough to
float the outbound IP around, even inside a v4 /24, then they should
expect their reputation to stay on the side of "low". If they do it
inside a v6 /64, they're really crazy.