Re: Keywords for "SMTP Service Extension for Content Negotiation"

At 06:50 +0900 on 07/14/2002, Dave Crocker wrote about Re: Keywords 
for "SMTP Service Extension for Content  N:

>  >if the message being transmitted is a fax and all recipients are capable
>>of fax,
>>then perhaps it is acceptable to downgrade the message to a lower quality fax
>>format which is acceptable to all.
>
>Ever since multi-recipient addressing was introduced, we have had
>downgrading, by virtue of users having to choose the least common
>denominator approach to sending attachments.
>
>So the fact that this new mechanism allows that downgrading to happen later
>in the transmission sequence should not confuse anyone into thinking that
>downgrading is a new or unusual requirement.

?

There are ways of delaying the downgrading until the recipient has 
actually received the content (and thus gets the message they would 
have received if they were the sole addressee). One that is obvious 
is the use of Multi-Part/Alternative. The sender creates the 
"downgraded" versions that are acceptable/required and hands the full 
set off to EACH OF THE RECIPIENTS. Each one then selects the version 
THEY WANT from the supplied versions without any heavy-handed LCD 
interference by an intermediary just due to one of the addressees 
being unwilling/unable to accept one of the "Better" versions.

I differentiate this from the type of on-the-fly downgrading that 
occurs with 8-Bit->QP transforms during relay since the original 
message CONTENT gets delivered even after the transform (so long as 
the receiving MUA understands QP) unlike the LCD transform where the 
original content is replaced with a lower quality LCD version.