IMAP Mailing List configuration for messageboards does not work correctly.(the first folder is not inbox)

1. Login as the admin user.
2. As per the screenshots, place a message board portlet on a page.
3. Change the configuration for the message board portlet as follows:
3.1 Allow anonymous posting or use a defined user with a known email address for testing.
3.2 Set-up from address. enter one email address.
3.3 Enable message added email.
3.4 Enable message updated email.
3.5 Scope to GLOBAL.
4. Create a new category.
5. Enable mail listing for category, using;
6.1 IMAP account - in our case it was a Gmail IMAP account. Please refer Mailing_List_Configuration.jpg
7. Login as a valid test user with an email address that you can monitor.
8. Subscribe test user to the test category.
9. Create a new thread within the category as some other test user
10. Debug code in MailingListMessageListener.java, as the followings
When using protocol = imap, please see the below test result:

Folder[] folders = defaultFolder.list(); //folders[6] [Follow up, INBOX, Misc, Priority, Trash, [Gmail]]
....
Folder folder = folders[0]; // folder is Follow up

In 81 line messages = folder.getMessages(); // messages is "".
Due to the folder is not inbox, so the issue occured.