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SpamDunk procmail filter 1999/04/25

1999-04-25 19:34:56
  The most recent update is April 25/1999. People with recent
versions of SpamDunk need only download
http://www.interlog.com/~waltdnes/spamdunk/sdfiles/NOTLIST.TXT
and save it as a textfile and upload as "isnotlist" To download
the system in its entirety see instructions at
http://www.interlog.com/~waltdnes/spamdunk/spamdunk.htm
Reasons for update... 
  - The big news is the implementation of procmail code to check
the IP address of incoming email against DSSL/DUL/ORBS/RBL lists.
You can tweak the code to remove services or add new ones. There
is no C-code executable required to be installed. DNS lookups are
performed by invoking "nslookup", which comes as part of the
standard unix installation on your ISP's server. I've also coded
the recipe to test only IP addresses that do not have your ISP's
domain name in their DNS/rDNS. That means that you don't have to
set up a list to exempt dial-ups at your own ISP from the DSSL
and DUL filters. 
  - Relay-checking via ORBS/RBL allows removal of my
"2-domain-relay-check-recipe". It was a great idea a year ago.
However, circumstances have changed... 
    - The filter rejected *ALL* relays, i.e. any email which
      passed through a 3rd domain between the sender and the
      recipient. There has been an increasing number of
      *AUTHORIZED* relays springing up, which generated
      false-positives. IPASS is one example. Also cable companies
      and phone companies have been banding together under brand-
      names like @home and Sympatico. That results in email from
      them showing an extra domain name, which tripped the filter.
    - Microsoft (There's a right way, a wrong way, and Microsoft's
      way) decided to do strange things with the "Message-Id:"
      header in their email clients. This sabotaged my code that
      parsed the sender's domain from the "Message-Id:" header. I
      still use it to check email claiming to be from popular
      free-email services, which have web interfaces and send their
      email with sane headers.

  - I've now extended the SMI-8.6 filter to SGI.8.6, which is
    also hard-coded wide-open for relaying whilst hiding the
    originating IP address.

-- 
Walter Dnes <waltdnes(_at_)interlog(_dot_)com> procmail spamfilter
http://www.interlog.com/~waltdnes/spamdunk/spamdunk.htm
Why a fiscal conservative opposes Toronto 2008 OWE-lympics
http://www.interlog.com/~waltdnes/owe-lympics/owe-lympics.htm

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