After an su root, I run "/bin/mail -u root" to check for
any mail that has arrived for root.  It doesn't find any,
and reports "No mail for root".  However, I can see that
there is mail in root's mailbox
file, /var/spool/mail/root.  Furthermore,
running "/bin/mail -f /var/spool/mail/root" allows me to
access it.  The problem here is that "mail -u user" is
(according to the man page) supposed to be eqivalent
to "mail -f /var/spool/mail/user".  It obviously is not
working correctly.