You may want to grant the relay for that network using Relay policy for objects which is accesible at Mail->General->Settings.
Firstly, you need to create an object at Objects->Add new, which is basically a set of network addresses. In your case, you may add an object called "mail relay" whose single member is network1 whose IP address is 192.168.1.0/24. Then, set this object as allowed object to relay.
I hope this helps to avoid editing a configuration file or template.