Re: Some thoughts on SMTP Verification

Yakov Shafranovich <[email protected]> wrote:
> What kind of data that we are looking for can help us with that? Would 
> passing some metadata about the message via SMTP or some other mechanism 
> help? What kind of metadata would it be?

  Metadata which consists of hints as to common interest would be a
start.

  e.g. "Patch for your program FOO"
  e.g. "discussion of last night's date"

  Some of this is already available in the message body, but not in a
form easily accessible to the MTA.  If it were to be in a form easily
accessible to the MTA, it would look like some kind of token-passing
scheme.  Whether or not such a scheme would be immune to spammers is
another question.

> And if spammers lie about that data, what do we do - reject the email? 

  If I'm lied to in a conversation, then my inclination is to walk
away.

> How would we handle spam sent via hijacked computer and routed through 
> an ISPs MTA?

  Punish the MTA.  If I can prove a spam came from your site, it's in
my interests to "discuss" that problem with you, e.g. by complaining,
or by sending two large men with baseball bats..,

  The email workload is currently biased against recipients.  Spammers
can pay money for large computers & bandwidth to overload many
recipients, but it's difficult for those recipients to coordinate with
each other to figh spam.  Everyone has their own favourite system, and
they don't cooperate.

  So *any* standardized anti-spam system would be a huge leap forward,
if only because it would have a groundswell of support, and enable
cooperation.

> This kind of like the "chain of trust" used in PGP. Sounds like an 
> interesting idea to me! What would spammers do in theory to get around 
> such system?

  Attack the holder of the trust.  If it's distributed, it's harder to
attack, but it's also harder to trust.  The benefit of having a
centralized holder of trust is that if they're attacked, they can mark
the owner of the attacking network as "untrustworthy", and they'll
watch all of their messages get rejected.

  This is an interesting business for someone with deep pockets, and
who lives in a non-litigious country.

> On the other hand any long-lived repository can be abused.

  See "Google".  Their capital is not in their search techology,
though that is a key element.  Their capital is the social trust
they've built up.  Altavista had it, and it disappeared once they p[ut
the needs of the advertisers higher than that of their users.

  So any "trust" repository has it's social capital depleted the
instant people decide not to trust it.

> > [ hints as to content ]
> 
> The spammers can lie about that, would we reject email that does not 
> match the extension?

  You can't establish informed consent if people lie to you.  At the
minimum, it's a reason to treat their messages with great suspicion.

  Alan DeKok.