Subject: Re: [Asrg] Default SPF Enablement?

From: "Jon Kyme" <[email-masked]>
Date: Thu, 02 Feb 2006 10:25:36 +0000

> > So, we inform the "original sender" that the *forwarded to* address
> (which
> > they may never have heard of) is broken? How useful is this?
> 

Seth Breidbart:

> 
> When I can read the headers to determine who forwarded it (so I know
> who I sent it to), that's quite useful.
> 

The 'owner' of the forwarding doesn't get to know that there's something
wrong. This is a pity. Also, the forwarding is exposed to the sender (as
you point out) which might be (in some circumstances) a significant leak of
(private) information. Perhaps it would be better for forwarders to accept
responsibility for the mail they generate (remembering the mapping so that
they can produce appropriate DSNs) and stop pretending to be relays.

As far as I'm aware the strongest objection to a well-designed sender
rewriting scheme is that it imposes costs on operators of forwarding
systems (while providing some small benefits to their users and to
senders).

Actually - having just read wot I wrote - another obvious objection is that
in the absence of something like SPF there's no urgent need for something
like SRS, although it would address the issues of loss and leakage of
information (as above) which will occur in traditional forwarding.

John Levine:
>When it's a bounce of an actual no kidding message and I can look at
>what's quoted in the bounce to see what I wrote, extremely useful.

I find that my messages usually bounce for reasons not depending on body
content. Often, the last thing I'd want is another copy of the message - I
have one in 'Sent' already. The address I sent it to and the Subject would
normally be enough for me. Do DSNs always include the body? Must they? And
anyway - who's saying that bounces be done away with? Isn't the point that
they should explicitly refer to the address that the sender used. Isn't
this what a SRS forwarder would do? 'Unwrap' (or lookup) the address and
'Forward' the bounce to the original sender?

JL:
>Sometimes I get the impression that people who attempt to design mail
>systems don't actually use them.

Thanks for sharing your "impression" with us.

Rgds,
JRK

Rgds

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From: John Levine <[email-masked]>
Date: 2 Feb 2006 16:11:52 -0000

>systems (while providing some small benefits to their users and to

The strongest objection of which I'm aware is that nobody does it, and
few people are likely to do it, so any design that depends on sender
rewriting isn't going to work.

>normally be enough for me. Do DSNs always include the body? Must they?

Read the RFCs and figure it out for yourself.  But they do have enough
to recognize the bouncing message.

> And anyway - who's saying that bounces be done away with?

Practically speaking, you are, saying the bounce should go back to the
forwarder rather than the original sender.  In my experience, there's
rarely anyone paying attention at the forwarding host.  On my system,
for example, I let people set up their own forwards, and I chronically
have problems where they set up a forward, but out of caution or
intattention still have mail delivered locally, and then forget about
the local mailbox which fills up and overflows.  If you don't send the
bounces back to the original sender, nobody's going to see them.

If people want to do sender rewriting, essentially treating forwards
as a one-member mailing list with a robot to catch the bounces and
turn off the forward (and perhaps the orignal address) if there are a
lot of bounces, that's not evil or anything, but it's never been the
standard way to forward mail and I don't see any likelihood that it
ever will be.

R's,
John

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From: "Jon Kyme" <[email-masked]>
Date: Fri, 03 Feb 2006 09:29:11 +0000

John Levine:

>as a one-member mailing list with a robot to catch the bounces [...]
that's not evil or anything [...]

Quite.