[EAI] "7. Upgrading downgraded header" (Re: I-D ACTION:draft-ietf-eai-downgrade-03.txt)

[Kari Hurtta <hurtta+gmane at siilo.fmi.fi>]

Internet-Drafts at ietf.org writes in gmane.ietf.ima:

> A New Internet-Draft is available from the on-line Internet-Drafts 
> directories.
> This draft is a work item of the Email Address Internationalization Working Group of the IETF.
> 
> 	Title		: Downgrading mechanism for Email Address Internationalization
> 	Author(s)	: Y. Yoneya, K. Fujiwara
> 	Filename	: draft-ietf-eai-downgrade-03.txt
> 	Pages		: 18
> 	Date		: 2007-3-8
> 	
> Traditional mail systems handle only US-ASCII characters in SMTP
>    envelope and mail header fields.  The Email Address
>    Internationalization is implemented by allowing UTF-8 characters in
>    SMTP envelope and mail header fields (UTF8SMTP).  To deliver Non-
>    ASCII mail address via UTF8SMTP non-compliant environment, some sort
>    of converting mechanism (i.e. downgrading) is required.  This
>    document describes requirements for downgrading, SMTP downgrading,
>    Email header downgrading and implementation consideration.

| o  If each mail header has [RFC2047] encoded part and which encoding
|      is "UTF-8", it may be a downgraded header, so decode it.

That algorithm not necessary produce original result. 

But perhaps it is determined that sequence first downgrade and then upgrade
does not need produce original result ?

Because on downgrade  only header field which was RFC2047 encodes was:
|   Subject:
|      Encode the header by [RFC2047] with UTF-8 tag and replace it.

that upgrade rule can be:

| o  If Subject: header field has [RFC2047] encoded part and which encoding
|      is "UTF-8", it may be a downgraded header, so decode it.

/ Kari Hurtta


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