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DynIP mail blocking considered harmful (was: Re: My email is rejected by some sites)

on Tue, Dec 16, 2003 at 09:09:18PM +0000, Colin Watson (cjwatson@debian.org) wrote:
> On Tue, Dec 16, 2003 at 01:34:03PM -0700, Wesley J Landaker wrote:
> > On Tuesday 16 December 2003 1:08 pm, Joerg Rossdeutscher wrote:
> > > A mailserver can harm _others_.
> > 
> > I totally agree. Which is why I'm all for only allowing arbitrary 
> > entities to determine who can and can not run a mail server. What we 
> > need is more control, more censorship, more penalties, and less 
> > interference from subvertive terrorists who try to route their mail 
> > around the system. The only reason they have to be doing something like 
> > this would be if they had something to hide. I believe that their 
> > computers should be confiscated and their citizenship revoked.
> Let's turn this around: why should *I* be forced to accept mail coming
> from a dynamic IP, when statistically such mail appears much more likely
> to be spam or viruses? Who are you to tell me that I have to accept such
> mail?

Statistically, mail from any arbitrary source is more likely to be spam
or viruses, than not.

Statistically, mail from the US is more likely to be spam or viruses
than not.

> (If it's not obvious why direct mail from dynamic IP addresses is a
> favourite tool of spammers, it should be.)

Spammers will abuse what they can get their hands on.

My own response is:

  - IP-based discrimination is at best a blunt instrument.  Where
    applied against specific netblocks based on known history, it's at
    least actionable.  Even whole-country blocking works as a goad to
    encourage countries to start getting serious about securing their
    domain -- or downward-delegating such responsibilities.  These days,
    you can expect to find abuse@ and postmaster@ addresses to work for
    many domains in China, Korean, Hong Kong, and Taiwan.  Vastly
    improved over a couple of years ago.

  - Dynamic IP blocking is per se unaccountable.  There's nothing the
    owner of a particular address can do to secure the address which
    impacts the listing.  This isn't a listing based on behavior of the
    address.  It's a listing based on an independent attribute of the
    address.  Some users may be able to get their provider to remove
    IPs from residential/dialup lists, but not all.

  - There are highly specific filters and methods which can effectively
    discriminate between spam and non-spam content.  Activity-based
    lists, Bayesian and content-based filters, reputation systems,
    teergrubbing, rate-limiting, and the like.

> This is *not* censorship, by the way. 

No.  It's arbitrary discrimination.

And for your own personal email configuration, it's your call.

This isn't acceptable for general-purpose communications, however.  And
I'd suggest you look into common carrier laws as well (I'm somewhat
familiar with US statutes) as to showing preferences by customer.  I see
little distinction between this practice and the illegal real-estate and
insurance underwriting practice of redlining neighborhoods.

> Censorship is when the government represses your speech. 

NB: Not strictly true.

> > Oh yes, and blacks to the back of the bus, please; just be happy we
> > let you on at all.
> It's a weak argument that requires a comparison to racism to be heard,
> not to mention that it demeans the plight of those affected by racism.

The similarity is this:  a secondary indicator is being used to
establish an absolute preference for or against a specific activity.
Despite the known invalidity of this indicator in a large number of
cases.  And the existence of more specific, accurate discriminators.


Karsten M. Self <kmself@ix.netcom.com>        http://kmself.home.netcom.com/
 What Part of "Gestalt" don't you understand?
  Backgrounder on the Caldera/SCO vs. IBM and Linux dispute.

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