Javamail不会获取所有邮件

Question

I am using the following configuration:

mail.pop3.ssl.enable "true"
mail.pop3s.socketFactory.class "javax.net.ssl.SSLSocketFactory" 
mail.pop3s.socketFactory.fallback "false" 
mail.pop3s.port "995"
mail.pop3s.socketFactory.port "995"
username "...@hotmail.com"
password "..."
host "pop3.live.com"

These properties are defined in an xml file, and loaded by the application into a Properties object.

And the following getter to fetch my emails:

public Message[] getMessages()
{
    // init variables
    Folder folder = null;
    Store store = null;
    Session session = null;

    // setup session
    try {
        session = Session.getInstance(props,
        new javax.mail.Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username, password);
            }
        });
        String protocol = host.contains("imap") ? "imaps" : "pop3";
        store = session.getStore(protocol);       
        store.connect(host, username, password);            
    } catch (NoSuchProviderException ex) {
        Logger.getLogger(Fetcher.class.getName()).log(Level.SEVERE, null, ex);
    } catch (MessagingException ex) {
        Logger.getLogger(Fetcher.class.getName()).log(Level.SEVERE, null, ex);
    }

    // read folder          
    try {
        folder = store.getFolder("INBOX");
    } catch (MessagingException ex) {
        Logger.getLogger(Fetcher.class.getName()).log(Level.SEVERE, null, ex);
    }
    try {
         if(!folder.isOpen())
            folder.open(Folder.READ_ONLY);
    } catch (MessagingException ex) {
        Logger.getLogger(Fetcher.class.getName()).log(Level.SEVERE, null, ex);
    }

     // get messages
    try {                       
        return folder.getMessages();
    } catch (MessagingException ex) {
        Logger.getLogger(Fetcher.class.getName()).log(Level.SEVERE, null, ex);
    }

    // default
    return new Message[]{};
}

This code works. It returns my emails. But for some reason, it does not return my most recent emails. It does however always return the emails starting at the same point in time (in other words, it always skips the same emails, so the behaviour is deterministic). These emails are all in my inbox (not in spam), they are varied, and not special in any way I can conceive.

What is going wrong?

Update (output of debug up until the first message):

DEBUG: setDebug: JavaMail version 1.4.5
DEBUG: getProvider() returning  javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLStore,Sun Microsystems, Inc]
DEBUG POP3: mail.pop3s.rsetbeforequit: false
DEBUG POP3: mail.pop3s.disabletop: false
DEBUG POP3: mail.pop3s.forgettopheaders: false
DEBUG POP3: mail.pop3s.cachewriteto: false
DEBUG POP3: mail.pop3s.filecache.enable: false
DEBUG POP3: mail.pop3s.keepmessagecontent: false
DEBUG POP3: mail.pop3s.starttls.enable: false
DEBUG POP3: mail.pop3s.starttls.required: false
DEBUG POP3: mail.pop3s.apop.enable: false
DEBUG POP3: mail.pop3s.disablecapa: false
DEBUG POP3: connecting to host "pop3.live.com", port 995, isSSL true
S: +OK DUB006-POP396 POP3 server ready
C: CAPA
S: -ERR unrecognized command
DEBUG POP3: authentication command trace suppressed
DEBUG POP3: authentication command succeeded
C: STAT
S: +OK 2256 257829688

C: NOOP
S: +OK
C: TOP 1 0
S: +OK

Answer 1

I had the same issue with an MS Exchange Mailbox. It is just a guess but in my opinion this can be a very common problem when using "modern" Email providers.

In my case it was because of message threading ("conversation view"): Somehow folder.getMessages() gets the # of conversations in your inbox instead of no. of messages and ends after that number. If you have 10 messages in your inbox, but 3 of them are grouped into one conversation, you only get the first 8 messages (7 messages plus 1 conversation).

Solution for me simply was:

• turn conversation view off in my inbox folder in the email providers web interface

• iterate all mails in an other way, avoiding .getMessages() :

   for (int i = 1; i < folder.getMessageCount()+1; i++) { Message m = folder.getMessage(i); ... }