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.
If you're talking about (broken) implementations, that's another
matter.