Do you want to view the Inboxes from different accounts in the same collective Inbox, or view mail from all folders of an account in its Inbox? Or, view all subfolders of Inbox, that you see in webmail?

I would like to view mail from all folders of an account in the inbox. Like you would have labels on Gmail.

One way would be to create a saved search from File/New/Saved Search, Choose... all the folders in the account, then 'Match all messages'.

Thanks! I've managed to create one.