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Re: [Nmh-workers] Wishlist item - beefing up slocal pattern matching

From: Mike O'Dell
Subject: Re: [Nmh-workers] Wishlist item - beefing up slocal pattern matching
Date: Sun, 25 Dec 2005 09:44:43 -0500
User-agent: Thunderbird 1.4 (Macintosh/20050908)

OOPS..... now you've stepped in it...

Having been through all this before, the first time 25 years ago
when RFC-733  was revised to give RFC-822, and all the
machinations since then...

both the specs and operational reality treat headers as
case-independent.  *if* you wish to honor case in header
processing involving pattern-matching, it MUST NOT be the default.
"slocal" in particular must honor arbitrary CaPiTaLiZaTiOn.

(0) the header tag to the left of the : is ALWAYS case-independent.
        the spec specifies how you *should* send it, but it
        required that the recipient to accept the header in spite
        of bizarre capitalization.

(1) anyone who created a new header with a case-sensitive data portion
        (to the right of the :) made a very, very bad design decision

(2) yes, i know base-64 can be used to encode the value of some
        extension headers (eg, X-foo), but that merely
        requires not screwing with the data in the header,
        which is already a requirement. if the processing
        of extention-header semantics wishes to honor case,
        that's fine, but *nothing else* is obliged to do so.

(3) ergo, it's still a bad decision to make headers case-sensitive

The fact that Postini made a very poor decision is no recommendation.

NOTE: Personally, I have always been on the side of honoring case in headers.
Especially now that we've admitted there are symbols outside the
26 letters of the US Roman alphabet, "case-folding" is really stupid
because it only applies to 26 symbols out of the 32,000 one can
use in Unicode-clean software.  I also happen to have an apostrophe
in my last name - a fact that almost always betrays the brain-damage
in Microsoft IIS web sites - and know many people with much more
exotic diacritical marks in their name, so i'm quite sensitive to
the "6-Bit-DEC10-ASCII-ization" imposed in the email RFCs.
(It wasn't that long ago that lower case was operationally
verboten in email text.)

however, the specs are the specs, and Postel's Robustness Principle:

        "Be conservative about what you send and
         liberal about what you receive."

is still very, very good advice.


Igor Sobrado wrote:
In message <address@hidden>, Joel Reicher writes:
I remember a while ago that people were wanting the slocal pattern
matching to be full regular expressions. I still think that is a good idea,
but it's occurred to me that the pattern matching of a maildelivery file
and the search criteria of pick do much the same job, so I'm now thinking
it would be a good idea for pick and slocal to share that machinery.
Any enhancement to pick would be an enhancement to slocal.

Since pick can do full boolean expressions, I think a new maildelivery
syntax might have to be introduced. That's the only part of this idea I
don't like.


I would like pattern matching to be case sensitive.  There are some
antispam services (e.g., Postini) that rely on capital letters on
user defined fields in the email header (those starting with "X-").
An example: http://spam.acm.org/public/filters/faq/postini_transf1.html

Don't know if standard fields in the message headers can be capitalized
in different ways, but it will certainly be useful to allow case-matching
at least as an optional feature.  On the other hand, Unix users are
accustomed to use the right capitalization for commands, filenames,
and so on...  ;-)

Just a wish...


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