Re: I-D ACTION:draft-palme-e-mail-translation-03.txt

> When the MIME standard was introduced, the handling by
> present mail was central in the design of mail. 

yes, to a point.  In particular, MIME was designed to allow
plain-text portions of MIME messages to be readable by 
existing UAs that could read plain-text RFC 822 messages.
This also influenced the default behavior of multipart/alternative,
in order to allow a plain-text alternative to be viewable
on an RFC 822 UA without the recipient having to skip over 
several screenfuls of base64-encoded material.

But MIME didn't attempt to provide new features in existing
user agents.