Subject: RE: [Asrg] Filtering spam by detecting 'anti-Bayesian' elements?

From: "Brian Azzopardi" <[email-masked]>
Date: Wed, 22 Sep 2004 09:19:01 +0200

I agree with you on the effectiveness of statistical filters for
personal use.

However, I wouldn't be so quick to dismiss them for corporate use. My
observations are that most corporate email is internal and that only a
relatively small portion of employees need to receive work-related mail
from external sources - in particular sales, marketing and other outward
facing staff. So for small to medium companies it works great.

Large multinations and ISPs are a different matter altogether...

Brian Azzopardi

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Jose Marcio Martins da Cruz
Sent: Tuesday, September 21, 2004 11:37 AM
To: [email-masked]
Cc: ASRG
Subject: Re: [Asrg] Filtering spam by detecting 'anti-Bayesian'
elements?

...

You're completely right on all this affirmations. What I really wanted 
to say is that statistical filters are very, very good for personnal 
use, but not for corporate structures. And most of the time I hear about

bayesian/statistical filters, this particular point is left...

-- 
  ---------------------------------------------------------------
  Jose Marcio MARTINS DA CRUZ           Tel. :(33) 01.40.51.93.41
  Ecole des Mines de Paris              http://j-chkmail.ensmp.fr
  60, bd Saint Michel                http://www.ensmp.fr/~martins
  75272 - PARIS CEDEX 06      mailto:[email-masked]

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From: Jose Marcio Martins da Cruz <[email-masked]>
Date: Wed, 22 Sep 2004 10:17:59 +0200

> Large multinations and ISPs are a different matter altogether...

Yeah ! The real problem isn't personal or not, but how much the 
population is homogeneous. Statistical filters may work very well with a 
very big population, as long as the trafic is homogeneous.

This is an optimisation problem - for a big population you have many 
local optimum values for the filter and global optimum values. The more 
all these values are near, the more your bayesian filter will be 
efficient on a big population. Unless you use one set of parameters per 
user...