Reading from javamail takes a long time

Question

I use javamail to read mails from an exchage account using IMAP protocol. Those mails are in plain format and its contents are XMLs.

Almost all those mails have short size (usually under 100Kb). However, sometimes I have to deal with large mails (about 10Mb-15Mb). For example, yesterday I received an email which was 13Mb size. It took more than 50min just to read it. Is it normal? Is there a way to increase its performance? The code is:

Session sesion = Session.getInstance(System.getProperties());
Store store = sesion.getStore("imap");
store.connect(host, user, passwd);
Folder inbox = store.getFolder("INBOX");
inbox.open(Folder.READ_WRITE);

Message[] messages = inbox.search(new FlagTerm(new Flags(Flags.Flag.SEEN), false));
for (int i = 0 ; i< messages.length ; i++){
    Object contents = messages[i].getContent();  // Here it takes 50 min on 13Mb mail
    // ...
}

Method that takes such a long time is messages[i].getContent(). What am I doing wrong? Any hint?

Thanks a lot and sorry for my english! ;)

Answer 1

I finally solved this issue and wanted to share.

The solution, at least the one that worked to me, was found in this site: http://www.oracle.com/technetwork/java/faq-135477.html#imapserverbug

So, my original code typed in my first post becomes to this:

Session sesion = Session.getInstance(System.getProperties());
Store store = sesion.getStore("imap");
store.connect(host, user, passwd);
Folder inbox = store.getFolder("INBOX");
inbox.open(Folder.READ_WRITE);

// Convert to MimeMessage after search 
MimeMessage[] messages = (MimeMessage[]) carpetaInbox.search(new FlagTerm(new Flags(Flags.Flag.SEEN), false));
for (int i = 0 ; i< messages.length ; i++){
    // Create a new message using MimeMessage copy constructor
    MimeMessage cmsg = new MimeMessage(messages[i]);
    // Use this message to read its contents 
    Object obj = cmsg.getContent(); 
// ....
}

The trick is, using MimeMessage() copy constructor, create a new MimeMessage and read its contents instead of original message. You should note that such object is not really connected to server, so any changes you make on it, like setting flags, won't take effect. Any change on message, have to be done on original message.

To sum up: This solution works reading large Plain Text mails (up to 15Mb) connecting to an Exchange Server using IMAP protocol. The times lowered from 51-55min to read a 13Mb mail, to 9seconds to read same mail. Unbelievable.

Hope this helps someone and sorry for English mistakes ;)