Ken Murchison <ken(_at_)oceana(_dot_)com> writes:
I find it interesting, if not disturbing, that some members of the
usenet community seem to think that mail messages and usenet articles
are not the same thing. AFAICT, from reading the relevant standards,
writing server code for SMTP/LMTP/IMAP/POP3/NNTP, and everyday use, mail
messages and news articles both conform to RFC 2822 (RFC 1036 states as
much). The only differences that I'm aware of are the following:
- usenet puts a greater restriction on the headers (although still being
RFC 2822 compliant)
Yes, although there are a variety of subtle things that fall into this
category that one has to be careful of. That's one of the difficulties
with Dan Kohn's existing draft; in dropping all of the language that was
completely unnecessarily copied from RFC 2822, he's also dropped some
language that's actually necessary.
Usenet's restrictions on the syntax of message ID headers are very
specific and very precise, and much stronger than those of RFC 2822, in
part because message IDs are used as part of the NNTP protocol. Comments
in various places that mail supports them are not well-supported by
currently deployed Usenet software (although it certainly hurts nothing to
support them when writing new code, other than adding complexity). The
space after the colon in headers is not optional on Usenet. The syntax of
the Date header is restricted in ways somewhat similar to that of the
Message-ID header.
- mail messages are typically tranmitted over a 1-to-1 protocol (SMTP)
and news articles are typically transmitted over a 1-to-many protocol
(NNTP)
Could somebody please enlighten me as to any others differences,
perceived or otherwise?
- National 8-bit character sets are in widespread use in Usenet message
headers, possibly more widespread than they are in (non-spam) mail
messages. Untagged 8-bit national character sets are widely used in
various non-English hierarchies in headers as the preferred way of
including such content, and in some cases use of RFC 2047 is frowned on.
Usenet was able to get away with that when e-mail couldn't because the
Usenet core software has always been 8-bit clean and because, due to the
more centralized nature of Usenet, it's possible to make determinations
like "every group in this hierarchy will be using this national character
set" and even encode them in news clients. It's much harder to know what
character set to expect in the general case in e-mail software.
- MIME never got very much uptake on Usenet for attachments. The binary
newsgroups are almost universally uuencode or, these days, yEnc. Base64
is rather rare and not at all popular. Binary readers and posters, for
reasons that I admit to really not understanding, seem to have had no
interest in the additional, cleaner semantics offered by MIME attachments
and continue to be happy with uuencode, scanning the body for telltale
lines, and doing guessing based on file names. Part of this may be due to
the fact that much of the Usenet binary traffic is split across multiple
posts and the MIME message/partial content-type is ill-suited to Usenet
for a wide variety of reasons. Just splitting a uuencoded file into
multiple parts is a lot easier (although it certainly makes decoding a
pain).
--
Russ Allbery (rra(_at_)stanford(_dot_)edu)
<http://www.eyrie.org/~eagle/>