My primary Domain runs on 192.168.75.25 and I am trying to setup a secondary domain on 192.168.75.26 I have another Secondary Domain on the 192.168.75.25 using port number 7103, I can install the new domain without any problems, but when I install the agent onto the 192.168.75.26 server, launching it, it does start up, and the MTA shows as open on the 192.168.75.26 server, but remains closed on the 192.168.75.25 server.

Is there something that I missed?
This is a testing machine but I am trying to better understand the setup for future knowledge.