On 2 Jan 2018, at 5:12 (-0500), Rupert Gallagher wrote:
This is the normative reference.
This is the OBSOLETED normative reference.
RFC 822, pg. 30, section 6.2.3
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msg-id = "<" addr-spec ">";
addr-spec = local-part "@" domain;
domain = sub-domain *("." sub-domain);
sub-domain = domain-ref / domain-literal;
<<a domain-ref must be THE official name of a registry, network, or
host>>
Note that the "@" must also be present as part of the
well-formed-formula.
When absent, the string is not well formed, and a syntax error occurs.
The change of formal syntax in RFC2822 to remove the reference to domain
entities was not inadvertent or surreptitious. RFC5322 didn't reverse
that change.
RFC 5322, pg. 27, section 3.6.4
---------------------------------------------------------------
<< The message identifier (msg-id) itself MUST be a globally unique
identifier for a message. The generator of the message identifier
MUST guarantee that the msg-id is unique. There are several
algorithms that can be used to accomplish this. Since the msg-id
has
a similar syntax to addr-spec (identical except that quoted
strings,
comments, and folding white space are not allowed), a good method
is
to put the domain name (or a domain literal IP address) of the host
on which the message identifier was created on the right-hand side
of
the "@" (since domain names and IP addresses are normally unique),
and put a combination of the current absolute date and time along
with some other currently unique (perhaps sequential) identifier
available on the system (for example, a process id number) on the
left-hand side. Though other algorithms will work, it is
RECOMMENDED
that the right-hand side contain some domain identifier (either of
the host itself or otherwise) such that the generator of the
message
identifier can guarantee the uniqueness of the left-hand side
within
the scope of that domain. >>
Note the use of RFC2119 terms. MUST and RECOMMENDED mean different
things.
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Currently Seeking Steady Work: https://linkedin.com/in/billcole
