Re: Fwd: New Version Notification for draft-crocker-email-deliveredto-05.txt

"John Levine" <[email protected]> 12 Aug 2021 22:49:44 -0400
Newsgroups gmane.ietf.smtp
Organization Taughannock Networks
Message-ID <[email protected]>
It appears that Ned Freed  <[email protected]> said:
>It's also different in that the use of the field in those MTAs is strictly for
>loop detection, which makes the format a local matter. The draft aims for a
>different - and in some cases disjoint - logging usage, which really calls for
>a common syntax.

As far as we know, all of the existing usage is for loop detection, so it would
be reasonable to say the contents of the header is a token or sequence of tokens
with semantics local to the MTA that adds the header.  I suppose we could say something
like what we say with Message-ID, to use a local domain to avoid collisions.

What is not reasonable is to overload this existing header with new, incompatible
semantics and no way to tell the difference.  The obvious solution, of course,
is to use a different header name.  If the goal is to record the SMTP envelope
address, Envelope-To seems to match what Exim does.  If the goal is something else,
make up a new header name.  It's not like they're hard to invent.

R's,
John