HP-UX System Administrator's Guide: Configuration Management

Edit the /etc/rc.config.d/mailservs file:
a. Set the SENDMAIL_SERVER environment variable to 1. Although you are
configuring a client computer in the workgroup, setting this environment
variable to 1 will start the sendmail daemon each time you boot your client
computer so that it can receive e-mail from other systems in your workgroup.
SENDMAIL_SERVER=1
b. Set the SENDMAIL_SERVER_NAME environment variable to the name of the
computer that will be the gateway to the outside world. For example, if the
gateway computer was called gateway.corp.com:
SENDMAIL_SERVER_NAME="gateway.corp.com"
c. (Optional) The environment variable SENDMAIL_FREEZE does not apply to
clients (which always freeze the sendmail configuration file), but it is
probably good practice to set this variable to 1 to indicate to viewers of the
/etc/rc.config.d/mailservs file that the sendmail configuration file
is being frozen for this client computer:
SENDMAIL_FREEZE=1
Configuring a System to Receive Electronic Mail 129