Subject: Bitter Pills (was Re: [Asrg] Re: RMX Records)

From: Mark Delany <[email-masked]>
Date: Mon, 3 Mar 2003 16:38:12 +0000

> That's a diffent problem we'll have to discuss. Unfortunately, 
> it will be difficult to disestablish empty envelopes in 
> common SMTP.

Lots of bitter pills. RMX only solves the forgery problem and it
potentially breaks:

A. forwarding

B. sending off-domain #1 (the roving user using a remote ISP)

C. sending off-domain #2 (the local user using a non-controlled domain,
  eg, I want to send email out from my ISP using my Yahoo address)

D. Raises the question of what to do with bounces

E. Probably requires a flag-day or implementation schedule. If RMX is
   ever to be useful beyond categorizing email - ie actually rejecting
   email as spam - then ISPs/providers will probably need to do this
   in concert to a) get a lot of buy-in and b) avoid a customer
   backlash like that experienced by Earthlink a month or so ago.

You could possibly address A) by doing envelope re-writing, but that's
currently considered bad-practice and presents a tricky issue for
subsequent bounces.

You could simply swallow the pill for B) and C) and say that's the
price we pay. (If RMX was close to a Silver Bullet, I for one would
happily accept the loss of off-domain mail submission.)

You could change SMTP to bounce with a semi-empty envelope, such as
<@example.com> to fix D) but that's more changes to SMTP.

And maybe if you try hard you might get the major ISPs/MSPs to agree
on a schedule to help E).

Then you're merely left with predicting how spammers will
respond. Will they adopt disposable/temporary domains making the
benefits of RMX largely moot? I doubt anyone knows for sure.

To my point.

None of what I've said has anything to do with RMX per se except to
suggest that any "solution" probably involves pills of varying
bitterness. Eventually we need to assess "solutions" based on:

	o how bitter they are
	o how effective they are
	o how permanent they are

I especially worry that we under-estimate the ability of the spamming
industry to morph. We need to consider them as motivated, smart and
none-too-fussed about breaking a few laws. Any "solution" that assumes
otherwise is probably at risk of taking much longer to implement than
it does to defeat.

Regards,
Mark.
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From: "Gary Feldman" <[email-masked]>
Date: Mon, 3 Mar 2003 12:15:29 -0500

> From: [email-masked] [mailto:[email-masked]] On 
> Behalf Of Mark Delany
> Sent: Monday, March 03, 2003 11:38 AM

> Lots of bitter pills. RMX only solves the forgery problem and 
> it potentially breaks:
> 

Let me point out that this boils down to "it solves the forgery
problem but breaks my ability to forge mail."

These are conflicting requirements.  The question is whether the
latter (the ability to forge mail, i.e. send mail from one place
that claims to come from another) is a legitimate requirement,
independently of the fact that it's a commonly cited requirement.

Is or isn't it reasonable for a recipient (whether end user or 
SMTP server) to refuse to accept email that claims to come from
one source if the system cannot authenticate that it really does?
Personally, I think not - there is no reason I should ever
accept mail that can't be authenticated.

Perhaps there is a two-fold solution: simple domain-based 
authentication such as suggsted with RMX, and cryptographic 
authentication for others.  For example, if you really want to be
able to use your ISP to send email that appears to come from your
Yahoo account, then include a PKI certificate that authenticates
you as the owner of the Yahoo account.  People who don't need
that ability need merely send mail from servers registered for
the domain of the purported mail sender.

Gary

---

From: "Mark Delany" <[email-masked]>
Date: 3 Mar 2003 17:48:28 +0000

> problem but breaks my ability to forge mail."

Exactly my point. Spam exploits features of email that some people
like and use, eg forging their own address.

Can we retain all of these oft-loved "features" and make an impact on
spam? I doubt it.

Regards.

---

From: Prasenjeet Dutta <[email-masked]>
Date: Mon, 03 Mar 2003 23:28:40 +0530

> you as the owner of the Yahoo account.

RMX + cryptographic verification is great because of one more reason: it 
solves a lot of problems for people who run their own mailservers 
(perhaps behind a residential DSL line). ISPs frequently block egress on 
port 25 because of people who run spam-spewing servers. With a way to 
identify these servers and hold them accountable, this could be a thing 
of the past.

I had written a (draft) paper on this sometime back (available here: 
<http://www.chaoszone.org/misc/spam.html>) where we were able to show 
that RMX + cryptographic verification was doable with a minimum of 
infrastructure changes (modern SMTP servers with plug-in mail processors 
would be able to handle the changes) and *no* protocol changes, and also 
a minimum of user-retraining, since cryptographic verification would not 
require novice users to maintain any keys with them: the keys would be 
maintained by the SMTP server administrator.

Regards
--Prasenjeet

==
Prasenjeet Dutta
http://www.chaoszone.org/