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.