这是我下面的代码，取自java教程——但是当我尝试接收从计算机发送的普通邮件时，我的问题就出现了，而不是通过GMail发送。如果我通过GMail收到电子邮件，它会运行正常并返回邮件，但是尝试从传统的桌面邮件客户端检索邮件会返回

错误：

java.lang.ClassCastException: java.lang.String cannot be cast to javax.mail.Multipart
at gridnotifierproject_pcbuild.HandleMailInput.retrieveOneMail(HandleMailInput.java:37)
at gridnotifierproject_pcbuild.GridNotifierProject_PCBuild.main(GridNotifierProject_PCBuild.java:22)

法典：

Properties props = new Properties();
    props.setProperty("mail.store.protocol", "imaps");
    try {   
        Session session = Session.getInstance(props, null);
        Store store = session.getStore();
        store.connect("imap.gmail.com", "***********@gmail.com", "******");
        System.out.println("Established Connection to Server!");
        Folder inbox = store.getFolder("Inbox");
        inbox.open(Folder.READ_ONLY);
        Message msg = inbox.getMessage(inbox.getMessageCount());
        System.out.println("Found specified Folder, retrieving the latest message...");
        Address[] in = msg.getFrom();
        for (Address address : in) {
            System.out.println("FROM:" + address.toString());
        }
        Multipart mp = (Multipart) msg.getContent();
        BodyPart bp = mp.getBodyPart(0);
        System.out.println("SENT DATE:" + msg.getSentDate());
        System.out.println("SUBJECT:" + msg.getSubject());
        System.out.println("CONTENT:" + bp.getContent());
    } catch (Exception mex) {
        mex.printStackTrace();
    }