Three major areas of concentration

On Tue, Mar 09, 2004 at 09:10:37PM -0600, wayne wrote:
| 
| I think it is likely that there will need to be completely separate
| proposals for:
| 
| 1)  The "is this IP address authorized to be an MTA?" question.
|     (e.g., MTA-Mark, SS, DUL lists, etc.)
| 
| 2)  The "is this IP address authorized to use a given domain name in
|     the MAIL FROM (and HELO) address?"  (e.g. RMX, SPF, DMP, etc.)
| 
| 3)  The "is this From: header from who it claims to be from?"  (GPG,
|     S/MIME, DomainKeys, Caller-ID, etc.)

I agree that these are three related but distinct areas; each deserves
consideration.

(1) has one dimension: is an IP address allowed to send mail?

(2) has two dimensions: is an IP address allowed to send mail *for a
    given domain?*

I prepared two documents for the Seoul BOF in which I tried to emphasize
the distinction between (1) and (2) above.

  http://dumbo.pobox.com/~mengwong/tmp/comparisons/buildyourown.png
  http://dumbo.pobox.com/~mengwong/tmp/comparisons/familytree.png

This little diagram may help illustrate the differences visually.

  http://dumbo.pobox.com/~mengwong/tmp/comparisons/2dimensions.gif

Today, DNSBLs filter along the IP dimension only.

In the future, with wide deployment of an SPF-like system, I hope that
accreditation and reputation services can help filter on the second
dimension as well.

cheers
meng