[mail-vet-discuss] What is the A-R header really for?

[Eric Allman]

--On October 16, 2007 10:57:04 AM -0700 Michael Thomas 
<mike at mtcc.com> wrote:

>> Thus, I do not believe that A-R is really for use in MUAs.  It is
>> to  pass information downstream without SMTP extensions.
>
> I don't see how these two things follow. Just because you don't
> want to show the raw auth-res (which I agree), doesn't mean that
> it's not for use in MUA's. Even if you believe it needs to be tied
> somehow to reputation, that doesn't mean that it has to happen
> before an MUA.

True, you could combine the A-R value with reputation in the MUA, but 
that implies that you're going to have some at least moderately 
sophisticated code in the MUA --- sophisticated enough that it can 
figure out which A-R fields are appropriate.  And I believe (i.e., it 
is my opinion) that in most cases combining reputation results will 
come before the MUA.

Perhaps I should say "I do not believe that A-R is really for use in 
basic filtering rules in MUAs, sieve scripts without special 
primitives included to combine A-R with reputation information, 
simple procmail scripts, or other such situations that do not involve 
writing some reasonably specific code to incorporate reputation 
information and which can therefore be sophisticated enough to 
determine whether a particular A-R field is associated with a 
relevant ADMD, and where by 'reputation' I mean reputation in the 
broad sense, not implying use of any particular technology, and 
including such related technologies as local white lists, 
accreditation, etc."  But that seemed a trifle verbose, and I somehow 
thought the meaning of my statement was clear enough.  I guess not.

eric