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[ietf-dkim] New Issue: Problems with Scenario 4: Resent

2006-09-20 20:00:18
Usage scenario #4 describes a requirement pertaining to "resent" mail,
but does not define exactly what resent means.

Is this simply mail that goes through MTA relaying, mail that is redirected via an MTA address alias, mail that is redirected by a recipient alias, mail that is re-posted such as by a mailing list, or what?

Text in the rest of the opening paragraph appears to intend resent to mean mail that is re-posted, that is, fully delivered to its initial addressee and then submitted again by the receiving user agent. There are a number of scenarios that re-post mail, including the user-level "forward" command. As such, the scenario, here, should describe precisely which specific scenario it means.

More generally, I cannot quite tell what this scenario is trying to demonstrate. As nearly as I can tell, all of the discussion about signing by Alice is irrelevant, since the later focus seems to be on signing by the re-poster, Bob.

At any rate, the language "a published practice of signing all messages sent from Alice's domain to Bob's mailing list" seems to suggest publishing per-recipient practices. I suspect that's not what was intended.

Possible alternate language:

     For example, Alice sends a message to Bob.  Alice's rfc2822.From
     field domain is used to sign the message and that domain publishes
     a statement that all mail with that domain in the From field is
     signed.

Lastly, the statement

     "Bob merely wants to assert his part in the chain of accountability
     for the benefit of the ultimate receivers. It would be useful for
     this practice to be encouraged as it gives a more accurate view of
     who handled the message"

implies that a long string of signatures by every node that handled the message would be a good idea.

Does the working group really believe that? I suspect there are some serious performance impact issues, here.

d/
--

  Dave Crocker
  Brandenburg InternetWorking
  bbiw.net


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