My ISP recognized this as a domain name but how do I determine a domain name from the list of stuff that I posted earlier? And, BTW, what does domain name mean?
For a compete explanation of a Domain Name see
this Wikipedia article. Until recently it was fairly easy to identify a domain name by looking for the Generic Top Level Domains (.com, .net, .org, .edu, .info) and Country Code Top Level Domains (.us, .au, .de, .fi, .fr, .jp, .kr,
etc. but recent changes in the rules have unleashed a plethora of Top Level Domain names which makes things much more difficult. The only thing I can suggest is looking for something that
looks like a domain name or follows the @ symbol. The IP addresses in parenthesis are also a clue.
To fully understand this puzzle you also need to understand
How To Read Email Headers. You might also try
this email header analyzer which by-the-way flags silverbackflow.com as blacklisted so that should probably be the one you are attempting to eliminate.