> -----Original Message-----
> From: Phil Pennock [mailto:pdp@exim.org]
> Sent: Thursday, May 12, 2011 4:14 PM
> To: Murray S. Kucherawy
> Cc: exim-users@???; technique@???
> Subject: Re: [exim] problem : x-vbr=hardfail
>
> If absence from a VBR list ever becomes a significant cause for concern
> by postmasters then Internet email will have become a system where we
> have to pay third party gatekeepers for permission to mail each other
> privately.
>
> I sincerely hope that this is never the case.
> [...]
VBR's assertions are fairly Boolean in nature; either the voucher makes the assertion about you or it doesn't (there is a DNS reply, or there is not). However, VBR isn't limited to the kinds of applications you're talking about, namely subjective things like "sends bad/good mail". It does have simpler applications, like being able to assert "this domain represents a real bank" which are less subjective especially if they are based on something like a government-run business registry. This could be very useful for reducing the effectiveness of phishing campaigns.
Pay-to-get-listed type services have existed for a while, and they have thus far not become the norm; many people don't use them specifically because they have an artificial quality to them. On the other hand, an open system that scores senders based on past observed behavior stands to be more neutral and beneficial. VBR could be used here too, but there's work afoot on a less Boolean system as well.
I'm doing a lot of tinkering on all of these things with OpenDKIM and, to a lesser extent, within the IETF. I'd love to talk more about it with interested people.
-MSK