ietf-822
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Re: Comments on draft-resnick-2822upd-02.txt

2007-08-28 09:48:14

In <01MKLM0UFGRY003GRV(_at_)mauve(_dot_)mrochek(_dot_)com> 
ned+ietf-822(_at_)mrochek(_dot_)com writes:

If this really is worth addressing (and I'm 99.99% convinced it is not), the
way to do it is to tighten down the rules, not loosen them. For example, you
could say something like "the 78 character limit SHOULD be observed when
initially constructing messages but exceeding 78 characters SHOULD NOT be 
taken
as justification for modifying messages in transit".

Yes, that would address my problem. In fact, it was one of the
possibilities I suggested, but Pete was unconvinced :-(.

Generally speaking, there should be a SHOULD NOT for changing _anything_
during transit, except for Trace headers, changes of CTE (if you are
unfortunate enough to encounter a non-8BITMIME system), or other such
things explicitly allowed. Far better to let the end points deal with
odd things that intermediate hops find odd.

Well, let's see. A _very_ incomplete list of legitimate things people do to
messages in transit would have to include:

Sure, but I was not suggesting that as a change to be incorporated in that
form at this time, but as a principle that we should move towards as and
when opportunity arises.

(1) MIME conversions - upgrading as well as downgrading
(2) Format conversions and transcoding (we have formally defined
   specifications for this)
(3) Signature addition, removal, and verification. (DKIM would fit in here.)
(4) Encryption, decryption, and reencryption
(5) Gateways to and from other message formats, arguably including netnews
(6) Various sorts of processing related to mailing lists. (IMO some of what's
   done is legiti, some isn't, but attempts to pin down the rules for this
   have beenn _spectacularly_ unsuccessful.)
(7) Spam and virus filtering, including but not limited to labelling,
   part removal, and viral payload excision.

Most of those affect only Trace headers (DKIM signatures are Trace
headers), or they are specifically allowed as part of related protocols.
Downgrading is fine (e.g. when passing to Non-8BITMIME systems); upgrading
is undesirable except maybe at the agent that does final delivery (it
breaks some signature algorithms). Likewise filtering is for final
delivery agents, and not at other points during transit. Gateways (that
inlcudes list expanders and other forms of forwarding) have of course to
provide whatever the ongoing medium requires, and maybe that involves
adding extra (trace-like) headers, but not removal or alteration of
anything that can possibly be avoided.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 Fax: +44 161 436 6133   Web: http://www.cs.man.ac.uk/~chl
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CHEADLE, SK8 3JU, U.K.
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