HP-UX System Administrator's Guide: Configuration Management

outgoing e-mail from the entire workgroup, even mail sent from a system that has NFS
mounted an electronic mailbox, appears to have originated on the hub computer.
Configuring the Hub
With Central Mail Hub topography, the electronic mail hub is the computer that receives
e-mail from any computer outside of the workgroup on behalf of its own users and
those of the client computers that it serves.
1. On the hub computer only, edit the file /etc/rc.config.d/mailservs:
a. Set the environment variable SENDMAIL_SERVER to 1 to indicate that this
computer is the hub computer:
SENDMAIL_SERVER=1
b. Set the environment variable SENDMAIL_SERVER_NAME to null to indicate
that no other computer serves this one:
SENDMAIL_SERVER_NAME=
c. (Optional) Set the environment variable SENDMAIL_FREEZE to 1 to indicate
that the sendmail configuration file is to be frozen. With older computers,
and in certain other circumstances, a frozen configuration file can speed up
sendmail’s performance by reducing the time it needs to parse its
configuration file.
SENDMAIL_FREEZE=1
2. Reboot the hub computer to start up and properly configure the sendmail daemon.
Configuring the Clients
With Central Mail Hub topography, the client computers do not receive electronic mail
directly. Users either log into the hub computer to process electronic mail, or they
NFS-mount their incoming mailbox files, typically located in the directory /var/mount,
and run a Mail User Agent on their client system to process their mail. For outgoing
mail (see “Configuring a System to Send Electronic Mail” (page 125)), the Mail User
Agent will automatically schedule the sendmail program.
Gateway Mail Hub Topography (Receiving E-mail)
This type of electronic mail system is similar to the Central Mail Hub topography in
that a single computer sends and receives e-mail on behalf of the all of the users in the
workgroup to and from computers outside of the workgroup. The difference is that e-mail
within the workgroup e-mail does not have to go through the hub computer because
each client machine is running its own copy of the sendmail daemon allowing it to
receive e-mail directly from other computers in the workgroup.
Configuring a System to Receive Electronic Mail 127