Compile a list of each of your mail clients, the locations of their mailboxes, and the names of the mail server systems.
Become root on the NIS master server.
Edit the /etc/mail/aliases file, and make the following entries:
Add an entry for each mail client.
Change the entry Postmaster: root to the mail address of the person who is designated as postmaster.
See "How to Set Up the Postmaster Alias" for more information.
If you have created a mailbox for administration of a mail server, create an entry for root:mailbox@mailserver.
Save the changes.
Edit the /etc/hosts file on the NIS master server and create an entry for each mail server.
Type cd /var/yp and press Return.
Type make and press Return.
The changes in the /etc/hosts and /etc/mail/aliases files are propagated to NIS slave systems. It takes a few minutes, at most, for the aliases to take effect.