How do I troubleshoot nonexistent domain name when using our domain name
If you are using Method 2 of your domain name, where you have created a unique 3 node domain name, like lists.xyz.com, and you get error messages that the domain name is non existent.
First step is to verify that you have set up the DNS correctly at a third party site like MX Toolbar or DNS Stuff.
Second step is to send an email to your list from a third party site like gmail.com or yahoo.com or any mail server that is off site.
If you can send email to the lists.xyz.com from off site, then the problem is internal.
Check that your out going 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 (lists.xyz.com) MX Records to your local DNS server. So that your outgoing mail server does not get confused with the entry for xyz.com
This is especially true for Microsoft Exchange servers.