Re: [dmarc-ietf] Definition of "value" in RFC8601

Damian Lukowski <rfc@arcsin.de> Tue, 31 March 2020 19:29 UTC

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From: Damian Lukowski <rfc@arcsin.de>
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Date: Tue, 31 Mar 2020 21:30:03 +0200
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Subject: Re: [dmarc-ietf] Definition of "value" in RFC8601
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>     > I don't see any reason to exclude them.  We could do this:
>     >
>     >       autbserv-id     = sub-domain *("." sub-domain)
>     >
>     > Where sub-domain is imported from 5321 for ASCII mail and 6531 for
>     EAI mail.
> 
>     Does this mean that a parser would need to know if the message has been
>     sent with SMTPUTF8 in order to pass or refute U-labels?
> 
> 
> You don't need SMTPUTF8 to handle IDNs.

I'm not sure if this answers my question. A parser for an ABNF grammar
needs to know the grammar. If the grammar is not fixed but depends on
external factors, the parser also needs to know the external factors. In
EML files that external factor is unavailable.