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Re: [ietf-dkim] DKIM on envelope level

2009-10-30 14:56:02
On 10/30/09 7:24 PM, John Levine wrote:
John mentioned CHUNKING.  The reason CHUNKING hasn't taken off is that ...
     
  ... the problem it was supposed to solve wasn't important.

In case it's not clear, I'm not saying that CHUNKING is a good idea.
But if for whatever reason you want the ability to abandon the
delivery between the headers and the body, CHUNKING lets you do that
without inventing anything new.

Signing the envelope strikes me as one of those things that sounds
nice, but when you try to work out the wa you'd use it in a practical
application, it turns out not to solve any interesting problems.
   

I can't say, but I do know that many of us toss a whole lot of mail at 
EHLO, some at MAIL FROM:<> and some at DATA.  The idea I was thinking 
about was whether it provides any value whatsoever to at least know that 
you are authentically dealing with a legitimate source sooner, without 
having to send even a whole header.  That having been said:
In particular, if the signature required an extra round trip for an
extra command, the delay would more than wipe out any speed increase.
   

I would probably modify the MAIL FROM: handling to do this such that no 
new roundtrips were needed.  That having been said, a DNS query would be 
needed, even if it's just to a caching resolver.
Also, it is not my impression that the mere data bytes of mail flowing
through networks are a particular problem.  If, for example, you
pipelined DKIM checks so you could tell that you could throw away the
body of an message as it arrived rather than storing it, how much
better would an envelope check be?
   
You and I are looking at two different problems.  I don't think that 
storage of the message is the issue, although there is a cost.  As I 
mentioned earlier, there are some sites that still pay a whole lot for 
bandwidth.

Eliot
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