Re: canonical MIME headers

> I've been looking through the various MIME specifications looking for a
> specific reference to a canonical form for MIME headers. 

there's not one.

furthermore, the set of transformations which are applied by widely-deployed
MTAs is such that it's probably impossible to define a canonical form such 
that canonical_form(source message) == canonical_form(delivered message)
with any reliability.

this is why all of the protocols for signing mail encapsulate the signed
message inside an attachment, and expect MTAs to treat the attachment as
an opaque object rather than (say) munging its header or translating its
content.

under those conditions there is no need for a unique and unambiguous 
representation of the headers.

Keith