Take a look at this example on how to read pop3 emails.
But there are 3 parameters you need to prepare: your pop3 server, username and passowrd for that server.

        String host = "<your pop3 server>";
        String user = "<your user name>";
        String password = "<your password>";
        String subjectSubstringToSearch = "Test E-Mail through Java";

        Session session = Session.getInstance(new Properties());

        try {
            // Get a Store object
            Store store = session.getStore("pop3");
            store.connect(host, user, password);

            // Get "INBOX" folder
            Folder fldr = store.getFolder("INBOX");

            fldr.open(Folder.READ_WRITE);

            int count = fldr.getMessageCount();
            System.out.println(count  + " total messages");

            // Message numbers start at 1
            for(int i = 1; i <= count; i++) {
                // Get  a message by its sequence number
                Message m = fldr.getMessage(i);

                // Get some headers
                Date date = m.getSentDate();
                Address [] from = m.getFrom();
                String subj = m.getSubject();
                String mimeType = m.getContentType();
                System.out.println(date + "\t" + from[0] + "\t" +
                                    subj + "\t" + mimeType);

               readContent(m);

                // Uncomment to set "delete" flag on the message
                //m.setFlag(Flags.Flag.DELETED,true);
            }

            // "true" actually deletes flagged messages from folder
            fldr.close(true);
            store.close();

Pretty straight forward, not much to explain.
All that is missing is the readContent() function which prints the message.getContent().

First you need to understand that an Email message content can be just a regular String or an input stream, but in most cases it is a Multipart object which can be composed of different parts of different types. It can also actually contain inner multiparts.

Take a look at readContent()

public static void readContent(Message m)
throws IOException, MessagingException{
    Object o = m.getContent();
    if (o instanceof String) {
          System.out.println(
          	"**This is a String Message**");
          System.out.println((String)o);
      }
      else if (o instanceof Multipart) {
          System.out.print(
          	"**This is a Multipart Message.  ");
          Multipart mp = (Multipart)o;
          int count3 = mp.getCount();
          System.out.println("It has " + count3 +
              " BodyParts in it**");
          for (int j = 0; j < count3; j++) {
              // Part are numbered starting at 0
              BodyPart b = mp.getBodyPart(j);
              String mimeType2 = b.getContentType();
              System.out.println( "BodyPart " +
              										 (j + 1) +
                                  " is of MimeType " +
                                   m.getContentType());

              Object o2 = b.getContent();
              if (o2 instanceof String) {
                  System.out.println(
                  	"**This is a String BodyPart**");
                  System.out.println((String)o2);
              }
              else if (o2 instanceof Multipart) {
                  System.out.print(
                      "**This BodyPart is a nested Multipart.");
                  Multipart mp2 = (Multipart)o2;
                  int count2 = mp2.getCount();
                  System.out.println("It has " + count2 +
                      "further BodyParts in it**");
              }
              else if (o2 instanceof InputStream) {
                  System.out.println(
                      "**This is an InputStream BodyPart**");
              }
          } //End of for
      }
      else if (o instanceof InputStream) {
          System.out.println("**This is an InputStream message**");
          InputStream is = (InputStream)o;
          // Assumes character content (not binary images)
          int c;
          while ((c = is.read()) != -1) {
              System.out.write(c);
          }
      }
	}

}

You will also need the mail.jar that can be found here.

download source

Java, JEE, pop3