Misuse of any protocol feature can cause interoperability problems.
ni8mc> But it is far from clear that the cases where X- field use is causing
ni8mc> problems actually constitute "misuse".
In fact I would say that this is an example of using the "protocol" exactly the
was intended, with an undesired, but entirely predictable, effect.
Alas, sometimes excellent intentions and even good designing/thinking
can produce very bad results. We simply have to acknowledge the outcome
and find a way to fix it.
When we added X-headers, I thought it was a very clever idea, indeed.
Instead it has proved both problematic and aesthetically ugly. (Since
email headers are user-visible, aesthetics matter, at least somewhat.)
My own, primary concern about them is having an "experimental" header
become a defacto standard and then having to find a way to get folks to
use a new, non-X header name for it. I believe that hasn't been
successful yet, or at least not much.
Dave Crocker <dcrocker-at-brandenburg-dot-com>
Brandenburg InternetWorking <www.brandenburg.com>
Sunnyvale, CA USA <tel:+1.408.246.8253>