import  java.io.*;
 import  java.util.*;

 import  javax.mail.*;
 import  javax.mail.internet.*;

...

String pop3server = "mail.some.com";
String pop3user = "login";
String pop3pass = "password";

Session session = Session.getDefaultInstance( new  Properties(),  null );
Store store = session.getStore("pop3");
store.connect(pop3server, pop3user, pop3pass);

Folder folder = store.getFolder("INBOX");
folder.open(Folder.READ_ONLY);
Message[] messages = folder.getMessages();
 for  ( int  i =  0 ; i < messages.length; i++) {
  Message message = messages[i];
  ...
}

folder.close(false);
store.close();