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Re: [ietf-822] utf8 messages

2014-08-15 17:23:36
On 2014-08-15 17:15, Daniel Vargha wrote:

On 15/08/2014 15:13, "Ned Freed" <ned(_dot_)freed(_at_)mrochek(_dot_)com> wrote:

On 14/08/2014 01:56, "Ned Freed" <ned(_dot_)freed(_at_)mrochek(_dot_)com> wrote:

I fully agree with Brandon, the standard SHOULD consider the use case
when a
message is transferred from one system to another as a blob (e.g.
flat
file) and
the only available "metadata" is that the message is in MIME format.
Having
some sort of well defined UTF8 indicator in the header section of the
message
would make it much simpler to adopt the new standard as it would
require
substantially less development effort in most cases.

I'm skeptical of the claim, but if you absolutely have to have
something,
why
not add a Received: field containing a "with smtputf8" clause, assuming
one
isn't there already?

Received: headers are not very reliable, and the syntax is is not well
defined.

On the contrary, it's quite well defined. See RFC 5321. The issue isn't
that
it's poorly defined, but rather that there are a lot of agents that don't
create it properly.

Maybe because it was defined too late, and not in the right place? (RFC
5321
is about SMTP not about MIME) From the parser's point of view the reason
is
indifferent, the reality is that it is better not to rely on it. Even RFC
5321
says:

"...receiving systems MUST NOT reject mail based on the format of a trace
header field and SHOULD be extremely robust in the light of unexpected
information or formats in those header fields."


Successfully parsing a Received: header itself requires a lot of
heuristics.

A full parse does, and so does looking for IP address information (which
doesn't appear directly as a clause value and whose position was only
standardized late in the game). Looking for a with clause with a
particular
value does not.

Looks like we have quite different ideas about reliability and parsing.
I certainly would not consider the partial parsing approach you suggested
as reliable.

It's only the topmost (last added) Received header field that is
to be considered here. It is added by your own mailer, and you
know exactly what software that is using. The topmost added
Received header field is always in the same format, its contents
is always trustworthy. It is likely RFC 5321 compliant, but even
if it is not, you already know and can rely on its idiosyncrasies.
So there is no good excuse for not fetching the WITH clause
from this field, if other ways of accessing the EAI flag are
not available.

  Mark

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