On 7/21/20 9:08 PM, John C Klensin wrote:
>> I think it's slightly deeper than that, which is that every
>> time one party adds a new header field, some number of other
>> parties decide that they can delete or modify that field, or
>> use it to validate or invalidate the message. So random
>> parties making random decisions about message headers are
>> detrimental to email reliability.
> I agree with that. But that is the justification for registered
> header field names, preferably well-documented and stable ones.
I suspect this is not an issue that can be addressed by any combination
of registration and/or field-naming constraints in the absence of
instructions to message-handling software about which fields (if any)
they can add, modify, or delete.
I love the format's extensibility but I suspect there's a point of
diminishing returns. The message header has become a garbage dumping
ground, and it might need some cleaning up.
Doors, once opened, are hard to close.
Building a door where none existed before is even more difficult. Especially
when the costs of construction have yet to be justified.
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