Brian E Carpenter <brian.e.carpenter@xxxxxxxxx> writes:
> I am disturbed that the messy situation of X- headers,
> created by RFC 2822's silence on the subject, has
> not been fixed.
Me too.
> I believe it would be appropriate to document that although
> X- headers are widely used, they are not part of the standard
> format and their treatment by Internet MTAs MUST NOT be relied on,
Agreed.
Further, one could discuss that using X- have caused interop problems
when standardizing the header field. Old applications only know about
the X- form and would not know the non-X- form, which makes it difficult
to standardize the X- header field. It may be preferable to avoid using
X- in experiment intended to be standardized later on. This point of
view may be more contentious than what you propose though. I'd be
interested to understand if others share this opinion.
> unless registered under RFC 3864.
I'd prefer to avoid this escape mechanism. Can X-* headers really be
registered under RFC 3864? RFC 822 says:
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.
...
extension-field =
<Any field which is defined in a document
published as a formal extension to this
specification; none will have names beginning
with the string "X-">
/Simon
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