You'll need a domain name with appropriate A and MX records for your mail server, at a bare minimum, to receive emails from the internet.
You can send mail without this (hell you can send email just by telnetting to port 25 on any public mail server, don't necessarily need your own server) but without your DNS records set correctly most modern systems will reject you as a spammer.
Why would you go to all the effort of setting up netware at all, let alone a version as ancient as 3? I assume you will be running an equally ancient version of Groupwise, Eudora or Pegasus?
I wouldn't put such an old version of the software on the internet, its full of bugs and vulnerabilities by now, plus you need to worry about anti virus/anti spam if you run your own mail server. At the very least make sure its not an open relay or you'll get blacklisted very quickly.
If you are squeamish, don't prod the beach rubble.