Regarding messages for the postmaster if you are using E-smith 4.0bx then there is an option on the "Other email settings" page of the web manger;
Root and Admin in E-Smith are different names for the same
person (who wears two different hats

Root is for logging
in at the console, where admin is used to access the
Web Manager or retrieve mail via pop.
> Change other email settings
>
> Administrative notices generated by the e-smith server are
> normally emailed to the admin account. If you would like them
> to be emailed elsewhere, please enter the email address below.
> Otherwise, leave this field blank.
>
> Forwarding address for __________________
> administrative notices: |__________________|
>
> Whenever the e-smith server receives a message to an unknown
> user, it can be returned to the sender with an error message
> (recommended > practice) or sent to your system administrator
> (as an administrative notice).
> =======================
> Email to unknown users: | Return to sender |^|
> | or Send to Admin v|
> ----------------------