On Thu, 18 Aug 1994, Ned Freed wrote:
Signatures are not sufficient, in that there are circumstances where even if
something is signed twenty times by all the angels in heaven cancellation,
obsoleting, or whatever should not and cannot be allowed.
Like Ned, I am also concerned about the advisability of allowing a header
than can perform mail message cancellation. Maybe what is needed is not an
"Obsoletes" header, but a "More-Recent-Than" header? The semantics of this
would be advisory only. It doesn't remove anything but gives compliant UA's
the ability to say "The originator has sent what he/she claims is a more
recent version of this. Do you want to see it?" but still display the
original unchanged in case a spoof is in progress. Anything else is just
too ripe for abuse.
I too have sometimes exclaimed, "Noooooo!! I didn't mean to send that!!",
and have wished I could reach out and grab a message before it left my
site (complete with physical hand groping motions :-) ). But them's
the breaks in this medium.
Just my 2 currency units worth. Adjust for local monetary system and add
salt as necessary.