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Re: Simple questions to start

1999-05-29 19:55:40
At 03:11 PM 5/28/99 +0300, Liviu Daia wrote:
On 27 May 1999, Stan Ryckman <stanr(_at_)sunspot(_dot_)tiac(_dot_)net> wrote:
At 02:57 AM 5/28/99 +0300, Liviu Daia wrote:

2. ^FROM (as apposed to ^From:) - Checks "From:", "Resent-by" and
similar header lines. True or False.

   [*Sigh*] False, please RTFM.  Unlike ^FROM_DAEMON and
^FROM_MAILER, ^FROM has no special meaning.  If you are doing
case-insensitive matching, it will match "From " and "From:" lines,
and that's all.

Well, yes, it has no special meaning; however, it technically *can*
match other header lines, such as:

    Fromage: cheddar

which, though there aren't any among RFC-specified headers, aren't
"illegal."

   IIRC, the RFC-blessed convention is that all non-standard headers
should have names starting with "X-".

IIRC, the "blessing" merely takes the form of promising not to standardize
in the future headers that start with "X-".  Therefore, for example,
mailer-writers would choose to use "X-Mailer:" rather than "Mailer:" so that
in case a later standard was developed to identify mailers, they wouldn't be
producing a mis-formatted headerfield.

(Turns out this particular one is now getting standardized as "User-Agent:"
anyway.  :-)

Cheers,
Stan

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