Re: anti-spam measures

From: Nigel Wade (nmw_at_ion.le.ac.uk)
Date: 06/29/04 

Date: Tue, 29 Jun 2004 12:20:26 +0100

On Mon, 28 Jun 2004 18:10:01 +0000, Grant Wagner wrote:

> Roedy Green wrote:
>
>> 3. technology. I see a new email delivery system evolving to
>> completely replace POP3/SMTP. It will have a number of features.
>>
>> a. automatic encryption, compression, digital signing.
>> b. full use of the 8-bit channels.
>> c. a sender pays receiver system so any spam that does leak through
>> still costs the spammer.
>> d. the best anti-spam thinking that is built in, suitable for
>> technopeasants.
>> e. suitable for exchanging large files, and common files.
>> f. ways to protect against denial of service attacks.
>> g. designed from the ground up for technopeasants. Everything is
>> automatic.
>>
>> The original email system was cooked up overnight as a demo. The
>> author surely never dreamed his system would be used almost unmodified
>> for planetary email scheme. It needs a major overhaul.
>
> There are things that can be done now, immediately, within the limitations
> of existing technology, to help fix some of the mess:
>
> <url: http://www.circleid.com/print/151_0_1_0/ />
>
> Unfortunately the organizations and individuals who run mail servers seem
> unwilling or unable to put this mechanism in place, or uninformed about
> the benefits of implementing such a scheme.

Probably it's more likely that administrators of email systems can see the
weaknesses of the method rather than focusing on the strengths. Even the
proponent of the system recognises it has problems and provides fixes for
the most glaring ones.

The most obvious one is that MX records identify systems which are setup
to *receive* email, not to send it. So, if an organisation has hosta setup
to send mail and hostb setup to receive it, what should happen is that
hostb has an MX record and hostb does not. That way, anyone attempting to
send mail to the organisation will lookup the MX record for the domain and
get hostb. If both hosta and hostb have MX records they are advertising
the fact that hosta and hostb receive mail. This is wrong. When a mail
server wishing to send to the domain asks for an MX record they may get
either hosta or hostb, but hosta won't accept the mail. The "fix" for this
suggested by the author is a kludge, and shows why many of these proposals
just don't stand up to scrutiny. 

-- 
Nigel Wade, System Administrator, Space Plasma Physics Group,
            University of Leicester, Leicester, LE1 7RH, UK 
E-mail :    nmw@ion.le.ac.uk 
Phone :     +44 (0)116 2523548, Fax : +44 (0)116 2523555

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