The Free On-line Dictionary of Computing (30 December 2018):

deboursification

    Removal of irrelevant newsgroups from the
   Newsgroups header of a followup.  The term applies
   particularly to the removal of frivolous groups added by one
   of the Kooks.

   See also: sneck.

   [Sam Spade anti-spam software].

   (1999-09-15)