[ietf-822. where the msg-id issue is being discussed, is copied]
Andrew Gierth wrote:
"Seth" == Seth Breidbart <sethb(_at_)panix(_dot_)com> writes:
>> It it were entirely up to me, and I had a clean start, I think I
>> would remove quoted-strings and quoted-pairs entirely from
>> msg-ids. But I doubt that is practicable at this stage.
Seth> Why? Is there actually software that uses them?
I've certainly seen quoted strings in mail message-ids; in fact the
original host for this list used them (in Resent-Message-ID).
The relevant question is does any existing software currently
have a need to generate them. If they were ever used, relegating
the construct to obs- syntax still provides for reading old
messages, and if a construct was never used, it could be dropped
entirely. Has quoted-pair within a no-fold-quote ever actually
been used in a msg-id?