Driver to email client not working

Question

For my class we are attempting to write our own email client. Our professor gave us the following driver. However when I attempt to compile the driver I get these errors:
MailClient.java:125: cannot find symbol
symbol  : variable envelope
location: class MailClient.SendListener
               SMTPConnection connection = new SMTPConnection(envelope);
                                                              ^
MailClient.java:126: cannot find symbol
symbol  : variable envelope
location: class MailClient.SendListener
               connection.send(envelope);Admittedly it could be something with the SMPTConnection code, as that is what we had to write. However I would have expected it to throw some sort of exception in there and it does not. Any help to figure out why the driver is not working would be appreciatted.
Code:
  import java.io.*;
   import java.net.*;
   import java.awt.*;
   import java.awt.event.*;
/* $Id: MailClient.java,v 1.7 1999/07/22 12:07:30 kangasha Exp $ */
* A simple mail client with a GUI for sending mail.
* @author Jussi Kangasharju
    public class MailClient extends Frame {
    /* The stuff for the GUI. */
      private Button btSend = new Button("Send");
      private Button btClear = new Button("Clear");
      private Button btQuit = new Button("Quit");
      private Label serverLabel = new Label("Local mailserver:");
      private TextField serverField = new TextField("", 40);
      private Label fromLabel = new Label("From:");
      private TextField fromField = new TextField("", 40);
      private Label toLabel = new Label("To:");
      private TextField toField = new TextField("", 40);
      private Label subjectLabel = new Label("Subject:");
      private TextField subjectField = new TextField("", 40);
      private Label messageLabel = new Label("Message:");
      private TextArea messageText = new TextArea(10, 40);
     * Create a new MailClient window with fields for entering all
     * the relevant information (From, To, Subject, and message).
       public MailClient() {
         super("Java Mailclient");
      /* Create panels for holding the fields. To make it look nice,
      create an extra panel for holding all the child panels. */
         Panel serverPanel = new Panel(new BorderLayout());
         Panel fromPanel = new Panel(new BorderLayout());
         Panel toPanel = new Panel(new BorderLayout());
         Panel subjectPanel = new Panel(new BorderLayout());
         Panel messagePanel = new Panel(new BorderLayout());
         serverPanel.add(serverLabel, BorderLayout.WEST);
         serverPanel.add(serverField, BorderLayout.CENTER);
         fromPanel.add(fromLabel, BorderLayout.WEST);
         fromPanel.add(fromField, BorderLayout.CENTER);
         toPanel.add(toLabel, BorderLayout.WEST);
         toPanel.add(toField, BorderLayout.CENTER);
         subjectPanel.add(subjectLabel, BorderLayout.WEST);
         subjectPanel.add(subjectField, BorderLayout.CENTER);
         messagePanel.add(messageLabel, BorderLayout.NORTH);     
         messagePanel.add(messageText, BorderLayout.CENTER);
         Panel fieldPanel = new Panel(new GridLayout(0, 1));
         fieldPanel.add(serverPanel);
         fieldPanel.add(fromPanel);
         fieldPanel.add(toPanel);
         fieldPanel.add(subjectPanel);
      /* Create a panel for the buttons and add listeners to the
      buttons. */
         Panel buttonPanel = new Panel(new GridLayout(1, 0));
         btSend.addActionListener(new SendListener());
         btClear.addActionListener(new ClearListener());
         btQuit.addActionListener(new QuitListener());
         buttonPanel.add(btSend);
         buttonPanel.add(btClear);
         buttonPanel.add(btQuit);
      /* Add, pack, and show. */
         add(fieldPanel, BorderLayout.NORTH);
         add(messagePanel, BorderLayout.CENTER);
         add(buttonPanel, BorderLayout.SOUTH);
         pack();
         show();
       static public void main(String argv[]) {
         new MailClient();
    /* Handler for the Send-button. */
       class SendListener implements ActionListener {
          public void actionPerformed(ActionEvent event) {
            System.out.println("Sending mail");
         /* Check that we have the local mailserver */
            if ((serverField.getText()).equals("")) {
               System.out.println("Need name of local mailserver!");
               return;
         /* Check that we have the sender and recipient. */
            if((fromField.getText()).equals("")) {
               System.out.println("Need sender!");
               return;
            if((toField.getText()).equals("")) {
               System.out.println("Need recipient!");
               return;
         /* Create the message */
            Message mailMessage = new Message(fromField.getText(),
                     toField.getText(),
                     subjectField.getText(),
                     messageText.getText());
         /* Check that the message is valid, i.e., sender and
          recipient addresses look ok. */
            if(!mailMessage.isValid()) {
               return;
         /* Create the envelope, open the connection and try to send
          the message. */
            try {
               Envelope envelope = new Envelope(mailMessage, serverField.getText());
                catch (UnknownHostException e) {
               /* If there is an error, do not go further */
                  return;
            try {
               SMTPConnection connection = new SMTPConnection(envelope);
               connection.send(envelope);
               connection.close();
                catch (IOException error) {
                  System.out.println("Sending failed: " + error);
                  return;
            System.out.println("Mail sent succesfully!");
    /* Clear the fields on the GUI. */
       class ClearListener implements ActionListener {
          public void actionPerformed(ActionEvent e) {
            System.out.println("Clearing fields");
            fromField.setText("");
            toField.setText("");
            subjectField.setText("");
            messageText.setText("");
    /* Quit. */
       class QuitListener implements ActionListener {
          public void actionPerformed(ActionEvent e) {
            System.exit(0);
   }

Answer 1

This is what I mean:
/* Create the envelope, open the connection and try to send the message. */
           Envelope envelope = null;
            try {
                 envelope = new Envelope(mailMessage, serverField.getText());
                catch (UnknownHostException e) {
               /* If there is an error, do not go further */
                  return;
            try {
               SMTPConnection connection = new SMTPConnection(envelope);
               connection.send(envelope);
               connection.close();
                catch (IOException error) {
                  System.out.println("Sending failed: " + error);
                  return;
            System.out.println("Mail sent succesfully!");