> The NIC says these TARLETON.EDU doesn't exist.
 
> If they don't exist, then where do these messages/files come from ???
 
You mean you're getting mail from there?  As of 1968 there was no
college or university named Tarleton in either the US or Canada.  I
don't have a more recent list handy.  There *is* however a BITNET node
named TARLETON.  It seems like a good bet that somebody at TARLETON has
misconfigured their mailer in anticipation of a domain registration that
is still in the works.
                                  John