SocketMail Server

Start Server: Run the ExecuteServer.bat if you have Windows, or execute the command:
java -jar Server.jar
This will make the server start running on port 5005 which is its default port.

SocketMail Client

Start Client: Run the ExecuteClient.bat if you have Windows, or execute the command:
java -jar Client.jar 127.0.0.1 5005
This will start the client app and connect it to the localhost on port 5005.
The first parameter sets the host and the second parameter sets the port. So, if you want to have the server app running on another computer, you will have to start the Client.jar with a first parameter being the ip of the other computer.