When creating a new receive connector on Exchange 2013 or 2016, you may run into this error:
The values that you specified for the Bindings and RemoteIPRanges parameters conflict with the settings on Receive connector "LITEX01\Default Frontend LITEX01". Receive connectors assigned to different Transport roles on a single server must listen on unique local IP address & port bindings.
When creating a receive connector, you choose one of two roles; either a Hub Transport connector or a Frontend Transport connector, as you can see in the screen shot below:
The problem is that the Frontend Transport Service is using port 25 for the Default Frontend Proxy <ServerName> receive connector and if you follow the defaults in the wizard, you’ll end up tying to create a new receive connector using the Transport Service which also listens on port 25. These two services run under different windows processes and they therefore cannot listen on the same port.
If you want to create a new receive connector that listen on port 25, you can do this but you have to create them it using the Frontend Transport role if you have either an Exchange 2016 server or an Exchange 2013 server with both the CAS and MBX roles installed on the same server.