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

Answer 1

Using the Folder.fetch method you can prefetch in one operation the metadata for multiple messages. That will reduce the time to process each message, but won't help that much with a huge message.

The handle huge message parts efficiently, you'll generally want to use the getInputStream method to process the data incrementally, rather than using the getContent method to read all the data in and create a huge String object with all the data.

You can also tune the fetching by specifying the "mail.imap.fetchsize" property, which defaults to 16384. If most of your messages are less than 100K, and you always need to read all of the data in the message, you might set the fetchsize to 100K. That will make small messages much faster and larger message more efficient.