If you are adding a postmaster mailbox to the aliases in the /etc/mail/aliases file, follow these instructions.
Become superuser or assume an equivalent role.
Roles contain authorizations and privileged commands. For more information about roles, see Configuring RBAC (Task Map) in System Administration Guide: Security Services.
Add an alias for root. Use the mail address of the person who is designated as the postmaster.
# cat /etc/mail/aliases .. root: email@example.com
Use the assigned address of the person who is designated as postmaster.
On the postmaster's local system, create an entry in the /etc/mail/aliases file that defines the name of the alias. sysadmin is an example. Also, include the path to the local mailbox.
# cat /etc/mail/aliases .. sysadmin: /usr/somewhere/somefile
Create a name for a new alias.
Use the path to the local mailbox.
Rebuild the alias database.