JPanel setSize/setPreferedSize not Working

I am currently working on nesting a jPanel inside of a jPanel, the code for which is

     Border loweredetched = BorderFactory.createEtchedBorder(EtchedBorder.LOWERED);
        jPanel1.setLayout(new GridLayout(0, 1, 0, 0));
        JPanel panel = new JPanel();
        panel.setBackground(Color.yellow);  
        panel.setLayout(new GridLayout(0, 1, 0, 0));
        JLabel someLabel = new JLabel("To: ");
        JLabel someLabel2 = new JLabel("From: ");
        JLabel someLabel3 = new JLabel("Date: ");
        JLabel someLabel14 = new JLabel("Email ");
        panel.add(someLabel);
        panel.add(someLabel2);
        panel.add(someLabel3);
        panel.add(new JSeparator());
        panel.add(someLabel14);
        panel.setBorder(loweredetched);
        panel.setPreferredSize((new Dimension(20,50)));
        panel.validate();

        jPanel1.add(panel);
        jPanel1.revalidate();

jPanel1 is the master pane with "panel" being used inside, as you can see from the SetPreferredSize I am trying to restrict the size of the internal panel but neither that, with dimension, or SetSize (int/Dimension) seem to be working correctly - the panel still fills the entire of jPanel1. Am I missing something obvious?

I am aware my naming conventions are poor but this is a simple demo program for playing around with the interface.

Thanks in advance,