(I'm totally guessing as to the component here)

On 7.2 release, installation creates an empty mail file for the nfsnobody
account.  One example:

$ ls -l /var/spool/mail
total 8

-rw-rw----    1 kaboom   kaboom             0 Sep 17 05:55 kaboom
-rw-rw----    1 nfsnobod nfsnobod           0 Sep 16 10:05 nfsnobody
-rw-------    1 root     root            7780 Sep 28 08:55 root
$
My guess is that it's being generated when the nfsnobody account is added?