and note that I didn't say 'indefinitely'. but lots of people keep
old mail around. while it's hard to argue that people should keep
buying 5.25" disk drives for the sake of reading their old floppies
(partially because the medium is essentially useless for storage of
new things), it's a bit easier to argue that MUAs should contain a
bit of extra code to handle slight differences in message format
that were once widely used.
That doesn't, however, imply that a standard should specify that
behavior.
no it doesn't imply that. however I believe it is appropriate for a
standard to do so, at least for several more years.
Keith