"Bruce" == Bruce Lilly <blilly(_at_)erols(_dot_)com> writes:
it is not, in fact, merely an NNTP issue; message-ids are a key
part of _every_ news transport method (since they are used to
detect duplicates). Every news server has to keep a history
database (or the moral equivalent) indexed by message-id, whether
it uses NNTP or not. Message-ids are passed around a lot
internally, stored in queue files, listed in ihave/sendme control
messages for UUCP feeding, appear as parameters in control
messages, and generally pervade the entire structure of news;
whitespace or excessive length breaks things in really quite a lot
of places.
Bruce> Andrew, you mentioned that the control characters and '>'
Bruce> which can appear (backslash-quoted inside a no-fold-quote) in
Bruce> a legal 2822 msg-id are problematic. Are those NNTP issues or
Bruce> implementation issues?
'>' is an implementation issue, in that probably the vast majority of
existing implementations take advantage of the RFC1036 restrictions on
message-ids to parse them simply by looking for the closing >.
(There are also implementations that treat '<' in message-ids as
invalid; I do not know why this is.)
NNTP itself does not have any problems with '>' that I know of.
I do not know the extent to which control characters other than TAB,
CR, LF (and NUL of course) actually cause any issues at the transport
level, though I expect some clients would have an interesting time
with them. I don't recall it coming up as an operational issue, unlike
ids with spaces or excessively long ids.
--
Andrew.