sendmail.cf
<messaging> {sendmail}'s configuration file, which it reads
once when starting up, usually found in the /etc directory.
Only real {Unix Gurus} can understand, let alone modify, this
file since it consists moslty of {header} {rewrite rules}
written as {M4} {macros}, as well as various other one- or
two-character commands.
(1996-12-09)