If you choose the PROXY_SMTP for the Proxy field, the Relay field appears below the Proxy field on the right side of the Rule Definition dialog window.
Choose whether you want to allow relaying of mail messages through the proxy in the Proxy Details area.
If you want to allow relaying, select the RELAY: ALLOW setting
If you do not want to allow the relaying, define the local domain name for the Screen or create a list of valid relay (domain) targets.
Create or edit the etc/defaultdomain file, to contain the domain suffix for the Screen
You must shut down and reboot the Screen for this default domain to become active.
Use the mail_relay feature of the ssadm command to create a list of valid relay (domain) targets (see the SunScreen Reference Manual manual).