Troubleshoot nonexistent domain name when using our domain name.
Using Method 2, you created a unique 3 node domain name like lists.xyz.com. Error messages appear saying the domain name is nonexistent.
Send an email to your List from a third party site (IE GMail or Yahoo).
If that email is successful, then the problem is internal.
Check that your outgoing mail server is pointing to valid DNS servers, to look up the domain name of outgoing email.
You may need to add the new domain name's MX Records (lists.xyz.com) to your local DNS server. This is so your outgoing mail server does not get confused with the entry for xyz.com
This is especially true for Microsoft Exchange servers.