sender/from/reply-to were major innovations in RFC 733, considerably
pre-dating SMTP.
d/
At 12:55 AM 2/13/2002 -0600, Pete Resnick wrote:
RFC 822 4.4.4 specifies Sender, defaulting to From, as the bounce target.
What was Crocker thinking? The envelope/message distinction was already
clear in SMTP. Why is Sender useful in a mail system that supports
envelope senders?
4.4.4 is not clear on whether it means bounces or other sorts of
notifications. For instance, a message from a human saying "This person
has a new e-mail address" would go back to the Sender since (e.g.) the
secretary would be the one interested in this information. Sender would be
the only reasonably readable place to find that information since at the
time, Return-Path would also have had a bunch of routing information,
might have a relatively useless address after the route, and it was rarely
generated.
----------
Dave Crocker <mailto:dcrocker(_at_)brandenburg(_dot_)com>
Brandenburg InternetWorking <http://www.brandenburg.com>
tel +1.408.246.8253; fax +1.408.273.6464