I have several email accounts and when I first nstalled The Bat I had a folder (I think it was Common Virtual) called 'Just In' which displayed all mail from all accounts as it came in.
When I had 'read' the message it disappeared from the 'Just In' folder (but, of course was left in its own Inbox folder).
The 'Just In' folder became corrupted and I had to delete it and have been trying to build another and set it up to display the contents of the indox of each account. I then set a filter based on Fast search 'Unread' and set it to work automatically.
Unfortunately, this only works if I manually force the filter which, of course, defeats the purpose.
Also, whilst it is possible to 'move' an email from 'Just In' to another folder, the move icon displays and the mail is dropped into the target folder but it still shows in Just In.