Question

After successfully opening Pop3Folder, and retrieving messages from it, I then sometimes get to the point, when folder.isOpen returns false. At the same time, when looking at the Pop3Folder‘s fields in debug mode, I see that the field opened set to true.

Could somebody give me a hint, what might go wrong here?

Here is the code:

public void popMail(MessageProcessor messageProcessor) throws MessagingException {
  Folder inboxFolder = null;
  Store store = null;
  try {
    store = mailSession.getStore();
    store.connect(mailSession.getProperty("mail.user"),
        mailSession.getProperty("mail.password"));
    // OK. Connected to POP3 Store.
    inboxFolder = store.getFolder("inbox");
    inboxFolder.open(Folder.READ_WRITE);
    // The folder is successfully opened.
    Message[] msgs = inboxFolder.getMessages();
    // Messages are successfully retrieved.
    if (msgs != null && msgs.length > 0) {
      for (Message msg : msgs) {
        if (messageProcessor != null) {
          // Calling custom listener to process message
          messageProcessor.processMessage(msg);
        }
        msg.setFlag(Flag.DELETED, true);
      }
    }
  } finally {
    // Oops, inboxFolder.isOpen returns false.
    // Meanwhile I see in debug mode that inboxFolder#opened is set to true
    if (inboxFolder != null && inboxFolder.isOpen()) {
      try {
        inboxFolder.close(true);
      } catch (MessagingException e) {
        log.warn("Error while closing folder");
      }
    } if (store != null) {
        try {
          store.close();
        } catch (MessagingException e) {
          log.warn("Error while closing store");
        }
      }
    }
}

Answer 1

The server may be timing out the connection if your processMessage method takes too long. Turn on Session debugging and examine the protocol trace for clues.