From: Charles Lindsey (chl@clw.cs.man.ac.uk)
Date: Tue Jun 13 2000 - 04:18:34 CDT
In <ylsnuibm2x.fsf@windlord.stanford.edu> Russ Allbery <rra@stanford.edu> writes:
>Maurizio Codogno <mau@beatles.cselt.it> writes:
>> I agree that message IDs SHOULD NOT be longer than 250 octects
>> (rather than characters).
>This is sufficient for me. SHOULD NOT is sufficient (at least to me) to
>use as justification for rejecting messages with longer message IDs. (And
>yes, octets should be used rather than characters, agreed.)
OK, the SHOULDs seem to have it so far, so here is now the complete
Message-ID text.
5.3. Message-ID
The Message-ID header contains the article's message identifier, a
unique identifier distinguishing the article from every other
article. The content syntax makes use of syntax defined in [MESSFOR],
subject to the following revised definition of no-fold-quote.
Message-ID-content = msg-id
id-left = dot-atom-text / no-fold-quote
no-fold-quote = DQUOTE *( strict-qtext / strict-quoted-pair ) DQUOTE
The msg-id SHOULD NOT be more than 250 octets in length.
NOTE: The syntax ensures that a msg-id is restricted to pure
US-ASCII (and is thus in strict compliance with [MESSFOR]). The
length restriction ensures that systems which accept message
identifiers as a parameter when retrieving an article (e.g.
[NNTP]) can rely on a bounded length. Observe that msg-id
includes the '<' and '>'.
[Do something about whitespace in dot-atom-text and no-fold-quote.]
Following the provisions of [MESSFOR], an agent generating an
article's message identifier MUST ensure that it is unique and that
it is NEVER reused. Moreover, even though commonly derived from the
domain name of the originating site (and domain names are case-
insensitive), a message identifier MUST NOT be altered in any way
during transport, or when copied (as into a References header), and
thus a simple (case-sensitive) comparison of octets will always
suffice to recognise that same message identifier wherever it
subsequently reappears.
NOTE: some old software may treat message identifiers that
differ only in case within their id-right part as equivalent,
and implementors of agents that generate message identifiers
should be aware of this.
-- Charles H. Lindsey ---------At Home, doing my own thing------------------------ Email: chl@clw.cs.man.ac.uk Web: http://www.cs.man.ac.uk/~chl Voice/Fax: +44 161 437 4506 Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K. PGP: 2C15F1A9 Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5