MRC@SU-SCORE.ARPA (Mark Crispin) (02/15/84)
From: "Benson I. Margulies" <Margulies@CISL-SERVICE-MULTICS.ARPA>
Subject: return path etc.
What does envelope-ness have to do with this?
Simple. Concepts such as the "origin address", the "composer
address", the "reply address", and the "return address [as
distinct from reply address]" should be specified in the message
envelope. At present SMTP only puts the "return address" and the
"destination address" in the envelope. The Return-Path header
line is generated by whatever process finally delivers the
message to the destination user (often the SMTP server but not
necessarily; in TOPS-20 it's the mailer), solely for the benefit
of other networks which don't have envelopes and depend upon the
header for everything.
A PC with a single 300 baud modem is not going to be pleased to have to
go calling up name servers for each address it wants to send mail to.
Of course not. But it is going to have to call up somebody to
start the message on its way. That somebody could also be the
name server. I'd rather have my PC calling up an intelligent
delivery agent that knows what I'm talking about than some stupid
forwarder that insists that I tell it everything.
I just checked, and the Multics mailer in fact implements my proposed
use of return-path -- as a way to send a reply back if the available
name resolving services don't make it.
Multics is not the specification. RFC's 821 and 822 are the
specification. All you've said is that the Multics mailer has a
bug that some individuals perceive as a feature. Past archives
of Header-People will document bugs in the TOPS-20 mailer that I
would protest is a feature.
The issue of "what mailbox at the source host to send errors to" as
opposed to "how did this mail get here" seems to deserve a seperate
field, probably in the envelope. The name return-path certainly
suggests my interpretation.
I'm afraid that RFC's 821 and 822 use Return-Path to mean the
former. And a non-trivial amount of software on a non-trivial
number of hosts implement it as this.
I'll tell you what. I'll agree to lobby with you to change the
meaning of Return-Path if you lobby to get the syntax of dates to
not require a comma after the day or week and to require a hyphen
before the time zone. It may sound silly to you, but it means a
good deal to TOPS-20.
Needless to say, both ideas probably would be rejected - and
should be.
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