小编jas*_*sop的帖子

我正在尝试以这种方式发送邮件：

Properties props = new Properties();
props.setProperty("mail.transport.protocol", "smtp");
props.setProperty("mail.host", "out.alice.it");
props.setProperty("mail.user", "mymail@domain.it");
props.setProperty("mail.password", "*****");
Session mailSession = Session.getDefaultInstance(props, null);
Transport transport = mailSession.getTransport();
MimeMessage message = new MimeMessage(mailSession);
message.setFrom(new InternetAddress("Host", "Name"));

在该行Transport transport...我检索到此错误：

javax.mail.NoSuchProviderException: Invalid protocol: null
    at javax.mail.Session.getProvider(Session.java:440)
    at javax.mail.Session.getTransport(Session.java:659)
    at javax.mail.Session.getTransport(Session.java:640)
    at javax.mail.Session.getTransport(Session.java:626)
    at Mail.sendMail(Mail.java:151)

我该如何解决？有人能帮我吗？谢谢！！:)

编辑：

如果我创建一个 main 并启动该方法来发送邮件，效果很好！当我将邮件读入邮件文件夹后，我的问题出现了：

Properties properties = System.getProperties();  
properties.setProperty("mail.store.protocol", "imap");  
Session session = Session.getDefaultInstance(properties, null);
Store store = session.getStore("pop3");
store.connect("pop3.domain.it", "mail@domain.it", "****");  
Folder inbox = store.getFolder("inbox");  
FlagTerm ft = new …