RE: [Asrg] C/R Thoughts: Take 1

Yakov Shafranovich <> Sun, 18 May 2003 18:58 UTC

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From: Yakov Shafranovich <>
Subject: RE: [Asrg] C/R Thoughts: Take 1
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Date: Sun, 18 May 2003 14:58:46 -0400

At 10:34 AM 5/18/2003 -0400, Eric Dean wrote:

> > 2. C/R systems need to have a standard way of identifying themselves
> > as such.  This avoids loops, and it let's us shunt them into an
> > appropriate handling queue.
>Yes, if a message has the C/R shouldn't be challenged.  Only
>challenge messages should use C/R headers.  We've discussed the issue
>regarding spammers using them...not using them.  The other recommendation is
>that the system be stateful and not constantly return the challenge
>messages.  If you send my demo account 20 messages, you get one challenge
>back.  Now, that's implementation-specific.  I would not suggest that a
>protocol require a system to be stateful..if mentioned at all.  However, I
>would recommend that C/R headers result in a suppressed challenge to avoid

One thing I wanted to mention is that a C/R system that has a white-list of 
verified senders, should probably verify the senders again every X months.

> > 3. As I've said before--any system that requires you to do something
> > other than just reply (e.g. read a graphic) needs to meet
> > accessibility standards.
>Yes, agreed.  And therefore, vendors that do stupid things will not sell
>their product and Darwinian nature will run it's course.  I'm not sure that
>we want to address the body or content of the challenge message..just the
>challenge headers.  Again, these are just my thoughts and am widely open to

A Turing test may not be able to meet accessibility standards but again are 
we seeking to distinguish between man and machine, or verify the email address.

> > 4. If you have a web based confirmation system, you should also have
> > an email-based one.  The fact that I can send you email does not mean
> > that I can access your web site.  (Think China, think road-warrier,
> > think third world.)
>Agreed.  I'm not trying to specify a web-based authentication method here or
>an SMTP-reply one.  I agree there should be such methods.  I guess, if the
>industry is naturally going in a certain direction, I would not intrude on
>their liberties.  However, if we all want to interwork...which is really
>what I am looking to Interworking for C/R Systems...then  we
>should identify the criteria.  Come to think of it, that's ALL I'm
>considering.  I just to provide an interworking method and not dictate to
>vendors how they should build their own systems...the market will figure
>that out.
>As a result, I will probably rename the draft to a C/R System Interworking

Since the C/R systems operate over SMTP, all parts of it should operate 
over SMTP including the replies.


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