At 08:16 AM 1/10/97 -0500, Vicki Richman wrote:
>Dave Crocker has written:
>> At 1:25 PM -0800 1/8/97, Vicki Richman wrote:
>> >That would be acceptable to me only if the original date is
>> >preserved, perhaps as 'X-Original-Date: '.
>> Good point, though I'd suggest "Posted-Date". (And the X- isn't
>Yes, "Posted" is better.
I'd be confused; would "Posted-Date" be the date originally mailed,
or the date received/sent by the list? And while X- may not be
required, it would be safer. From RFC 822:
Individual users of network mail are free to define and
use additional header fields. Such fields must have names
which are not already used in the current specification or in
any definitions of extension-fields, and the overall syntax of
these user-defined-fields must conform to this specification's
rules for delimiting and folding fields. Due to the
extension-field publishing process, the name of a user-
defined-field may be pre-empted
Note: The prefatory string "X-" will never be used in the
names of Extension-fields. This provides user-defined
fields with a protected set of names.
Anyway, using "Resent-Date:" for the list's date is best,
since the RFC's already make it available (and optional).
Eric Thomas has also already listed some good reasons for not
changing the original Date: field.
>I'd appreciate guidelines on the use of 'X-' for user or
>list headers. Or a pointer to where I can get them.
The RFC's specify that future RFC's won't define 'X-' headerfields :-)
(see above). Hence, many pieces of software have "adopted" these with
many meanings, but none are "official." A list of "known" ones would
be interesting to see, though probably not that useful. Some fairly
common ones off the top of my head:
X-Mailer: string identifying the MUA software
X-Original-xxx: the original value of a replaced "xxx" headerfield
X-Loop: used by autoresponder software; if mail arrives
with the same value (usually the email address)
it is not responded to, to avoid looping
X-URL: sometimes added when creating mail from "mailto"
on a web page
X-Sender: often added to identify mail posted through a
POP account or SMTP, where the sender can
put anything into the "From:" header (as I'm
doing here; if you look at the headers, you'll
see I'm mailing from one ISP with "From:"
pointing to a different ISP)
actually a Usenet header, telling DejaNews not
to archive the post, but usable in a gatewayed
Stan Ryckman (firstname.lastname@example.org)