[arc-discuss] Question for draft-andersen-arc-00.txt -- Ordering Trace Headers

John Levine johnl at taugh.com
Thu Nov 19 07:21:25 PST 2015


>Some people (myself included) interpret RFC 5321's specifying the 
>placement of the Received header as indicating that it is polite and 
>sensible for an MTA to add all header lines that it adds at the top of 
>the header, thereby causing them to be grouped in one place and making 
>subsequent analysis easier, although there are plenty of cases in real 
>email where this is not true. Specifying an additional constraint about 
>ordering within the headers added by a given MTA is perhaps a little too 
>picky.
>
>Either ordering is acceptable, so is almost any other ordering.

Given that the ARC headers have sequence numbers.  I'd say they SHOULD
be added at the top like any other trace headers but validators MUST
be able to accept them in any order and unscramble them.

As discussed before, it'd make more sense to have an
ARC-Authentication-Results header for each group of ARC-* headers
since the intermediate A-R results are often interesting.  To make
that work, rather than than ARC-A-R being a direct copy of the A-R,
it's a copy with "i=N CFWS" in front of the contents of the A-R
header.  That's easy to do and makes the whole thing
scramble-resistant.

R's,
John




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