On Fri, 8 Apr 2005, Bruce Lilly wrote:
On Fri April 8 2005 10:47, Tony Finch wrote:
On Fri, 1 Apr 2005, Bruce Lilly wrote:
Section 3.3 discusses message identifiers, but fails to note that the
Message-ID message header field is optional. It also alludes to
multiple identifiers, but does not note that Received fields may
incorporate a msg-id in the optional "id" component.
Though the id item in Received: fields is not necessarily a Message-ID;
it may also be an MTA's queue ID.
If we're talking about architecture as designed, the Received field as
defined in RFC 822 absolutely requires a msg-id, complete with
local-part, '@', domain, and angle brackets.
RFC 822 says:
Some transport services queue mail; the internal message iden-
tifier that is assigned to the message may be noted, using the
"id" parameter.
i.e. a queue ID not the value of the Message-ID field.
RFC 821 has a much more detailed specification of the syntax, which
disagrees with the syntax in RFC 822 about what appears after id in a
Received: field. The only example of a Received: field in either document
is
Received: from ABC.ARPA by XYZ.ARPA via TELENET with X25
id M12345 for Smith(_at_)PDQ(_dot_)ARPA ; 22 OCT 81 09:23:59
PDT
RFCs 2821 and 2822 fix the syntax confusion by making 2822 specify just
the name/value item metasyntax and leaving the details of ordering and
which names and values are valid to 2821. The latter says:
- The ID field MAY contain an "@" as suggested in RFC 822, but this
is not required.
ID = "ID" FWS String / msg-id CFWS
Tony.
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