[Esa-l]Answered my own question...

[Mark_Saunders]

I found the mstnef by domain reference at:
http://www.impsec.org/email-tools/sanitizer-configuration.html
It appears that ANY of the sanitizers environment variables can be
altered this way.
..I should have looked there first...

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     __ _                   ____
    / /(_)_ __  _   ___  __/  _ \ __  __ _  _  _
   / / | | '_ \| | | \ \/ /| |/ //  \/ _| |/ / /
  / /__| | | | | |_| |>  < | |\ \|()||(_|   <\ \
  \____/_|_| |_|\__,_/_/\_\|_| \_\__/\__|_^\_/_/
  mv $win /dev/null