> This message draft has In-Reply-To: and References: header lines,
> introduced by the default replcomps. How would those lines get
> through post?
nmh would learn that those are in the directive set, like `To', and
`Attach', and ideally something about their RFC format too so it can
check the validity of the user's value before letting it pass through to
> If a added a Foo: line to, the draft, what would block it?
Yes, the email wouldn't be sent. Processed directives, e.g. Attach,
would have been removed by this point. All that remains should be
directives nmh, post?, is willing to put on the wire, perhaps with
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