RE: regarding spam...

[Rama Kant <kant () adeptech com>]

These days a significant volume of SPAM is coming from some of those mass 
email distribution companies.  A large number of such companies do not care 
where the mailing lists come from; in fact they would very likely not even 
have a reverse name entry for their mail server's IP address.  This way 
they force an extra step in their identification.

Legality issue: Any organization has the right to refuse junk mail. As long 
as the decision to refuse mail lies with an organization, how can a vendor 
supplying the service be taken to court, e.g. website filter vendors simply 
provide a database of offensive sites. (Please note that I am not giving a 
legal advice here.)

For a while we have been kicking around ideas similar to Andrew Kalat's and 
implemented as Vipul's Razor  www.vipul.net.  The added dimension here is 
of certain implanted addresses.

In general the process may work as follows:
A hash is calculated of the content and added to a database.  Individual 
organizations may decide the tolerance limits on hash values based upon 
their own criteria.  Of course the tolerance limits have to be set to keep 
the false positives to a very low level.  Even if a service bureau 
calculates hashes for unsolicited messages, that bureau is really not 
making the decision on whether to allow such a message or reject it.

Building of junk mailing lists -- mostly the addresses are harvested from 
many different sources major among them are websites.  A given collection 
of websites will contain 'special-purpose' addresses to collect SPAM by 
service bureaus.  As soon as a SPAM is received at these addresses its hash 
is calculated and added to the database.

It is this database that is checked against, either remotely or locally 
(downloaded/updated frequently), for possible SPAM.  Based on an 
organization's policy the SPAM is appropriately dealt with.


Rama Kant                               Voice: 703.404.3775
Director of Engineering                 Direct: 703.477.3583
Adeptech Systems, Inc.                  Email: kant () adeptech com
1420 Spring Hill Road, Suite 600        http://www.adeptech.com
McLean, VA  22102

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