how to change the root user's name on FreeBSD 6.1 running postfix

[Paul Hamilton]

Hi,
 
I am running postfix on FreeBSD 4.11 and 6.1 servers.
 
In FreeBSD 4.11, you can run 'chsh root'  and edit the name to what you
want.  However, on my FreeBSD 6.1 servers, I still receive email addressed
from 'root unix'.   I would like to be able to differentiate the root mail
according to server the mail came from  :-)
 
Any idea's?
 
 
 
Regards,
 
Paul Hamilton
Busselton, 6280
Australia