Here is my main.inc.php file entry. Please check & verify.
$rcmail_config['drafts_mbox'] = 'Drafts';
// store spam messages in this mailbox
$rcmail_config['junk_mbox'] = 'Junk';
// store sent message is this mailbox
// leave blank if sent messages should not be stored
$rcmail_config['sent_mbox'] = 'Sent';
// move messages to this folder when deleting them
// leave blank if they should be deleted directly
$rcmail_config['trash_mbox'] = 'Trash';
// display these folders separately in the mailbox list.
// these folders will also be displayed with localized names
$rcmail_config['default_imap_folders'] = array('INBOX', 'Drafts', 'Sent', 'Junk', 'Trash');
// automatically create the above listed default folders on login
$rcmail_config['create_default_folders'] = TRUE;
Thanks,
Nishith.