[Asrg] Re: More e-mail oddities; SPF thoughts

[Frank Ellermann <nobody at xyzzy.claranet.de>]

der Mouse wrote:

> Well, I meant ".forward-style forwarding", by which I mean,
> forwarding such that when A sends mail to B, which forwards
> to C, then B's mailserver accepts the A->B transaction and
> generates a new SMTP transaction to C, with the same MAIL
> From as the first hop but a new RCPT To.

In other words 1123 5.3.6(a) with an unmodified MAIL FROM.

> If that's what you meant by "the originator as indicated
> in the Return-Path", well, then, "yes".

The bit about "the originator as indicated in the Return-Path"
was supposed to be a RfC 2821 quote, but I got it wrong, it's:

| If an SMTP server has accepted the task of relaying the mail
| and later finds that the destination is incorrect or that the
| mail cannot be delivered for some other reason, then it MUST
| construct an "undeliverable mail" notification message and
| send it to the originator of the undeliverable mail (as
| indicated by the reverse-path).

And yes, I think we must keep this MUST as is, and therefore we
can't keep 1123 5.3.6(a) as is, in a world with forged "reverse
paths" everywhere this causes havoc for innocent bystanders.

                              Bye, Frank



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