HP3000 E-Mail Configuration: Security Tips

For those sites with an HP 3000 system connected (somehow) to the Internet, there are a few specific security issues you might want to address:

Make use of existing security features on the HP 3000.
Secure logons which are not used regularly.
Implement third-party security packages or special tools to secure access to the machine.
Implement a firewall between your system and the Internet.
Configure your router to filter incoming traffic based on TCP ports.
Configure your router to prevent "IP Spoofing".