下面的代码使用javamail API来访问gmail,

    String host = "pop.gmail.com";
    int port = 995;
    Properties properties = new Properties();
    properties.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");

    final javax.mail.Session session = javax.mail.Session.getInstance(properties);
    store = session.getStore("pop3s");
    store.connect(host, port, mCredentialaNme, mCredentialApss);

// ***************************************************************
Folder personalFolders[] = store.getDefaultFolder().list( "*" );
    // ***************************************************************
    for (Folder object : personalFolders) {
        // ***********************************
        System.out.println( object.list("*") );    
        // ***********************************
        if ((object.getType() & javax.mail.Folder.HOLDS_MESSAGES) != 0){
            object.open(Folder.READ_ONLY);
            Message messes[] = object.getMessages();

            System.out.println(object.getFullName());
            System.out.println("====================");
            for (Message object1 : messes) {
                System.out.println(object1.getFrom() + " - " + object1.getSubject());
            }
            object.close(false);
        }
    }

if (store.isConnected()) {
        store.close();
    }

问题是此代码仅列出INBOX文件夹,而定义的标签不少于20个.
如何让代码列出/访问这些嵌套的文件夹/标签应该怎么做？

解决方法:

如果您想要标签/文件夹,请不要使用POP,请使用IMAP.

如javamail docs所述,由于POP协议的性质,POP消息存储始终存在

Contains only one folder, “INBOX”.