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ADMD (was: Re: I-D ACTION:draft-crocker-email-arch-06.txt)

2007-03-12 17:09:27


David MacQuigg wrote:
What are these strange "Transit" domains, and how do they get involved in a mailflow? Fig. 4 and the related text seem to imply that they are an independent part of a typical mailflow, outside the realm of either senders or receivers, and equal in stature to either of these.

I thought I had found such a beast in my own mailflow, but it turned out to be just another piece of the sender's network. My outgoing mail was going via, a server owned by Verizon. The folks at my local ISP,, didn't know why was in the loop, and told me that it was just something that was set up by their upstream provider.
Maybe we could clarify the draft with some words like:
The boundaries of an ADMD may be defined differently by each participant in a mail transfer, and the concept may still be useful even if there is no agreement, or even a clear definition, as to the boundaries.

Thank you for your thoughtful comments.

I think that your suggestion would be quite good, for a document that is attempting to describe things from the perspective of an end-user and for customer service representatives who assist end users. It is easy to forget that end-users see things far more simply than operators.

However the current architecture document has a different goal. To the extent that the concept of an ADMD is not sufficiently clear, then indeed that needs to be fixed.

The document's first use of the term "Administrative Management Domains (AdMD)" is preceded by the word "independent". Section 2.3 on Administrative actors repeats this point.

There are real boundaries between meaningfully different centers of control, along different parts of the email service. The concept of ADMD is intended to refer to these boundaries.

My company uses email transit through an independent company (songbird). I have my "operating policies" for email within my ADMD and Songbird has theirs. Believe me, no matter how well we get along, the independence between us is real and has an effect of aspects of the way email is handled between us, even though Songbird is "only" a transit for my mail.

In fact, this split between local (edge) email services and an ESP or transit provider is quite common.

Indeed you cited three common scenarios: "a large ISP, a small email service, and a professional association, all forwarded to a private mailbox at his own company". None of these is part of your organization or subordinate to it, though of course there is cooperation. But there is also independence.

As the "tussle" paper that I cite in the architecture document points out, these boundaries can have a profound effect on the ways a real-world service operates.

So, ADMD is intended to capture this concept of boundaries between independent spheres of control.


  Dave Crocker
  Brandenburg InternetWorking