unsubscribe emails

Why are we still seeing emails with "unsubscribe" subjects on the lists?
I thought we had a filter to auto-reply to them.

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----- Forwarded message from Bill Hernandez -----

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Message-ID: <7D4D50A9-6A46-4DE0-94F6-2593084BCB7A@mac-specialist.com>
To: pgsql-admin@postgresql.org
From: Bill Hernandez <pgsql@mac-specialist.com>
Subject: [ADMIN] unsubscribe
Date: Thu, 14 Dec 2006 09:28:30 -0600
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TIP 5: don't forget to increase your free space map settings
----- End of forwarded message from Bill Hernandez -----

--
  Bruce Momjian   bruce@momjian.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +