I have several accounts set up in TB, many with multiple sub-folders containing many emails.  Occasionally I need to add a new account with the same sub-folder structure containing copies of the emails from an existing account.  I would like to simply be able to create a copy of an existing account including all sub-folders and the emails they contain, then change whatever properties I need to in order to use a different set of servers and other settings.

However, I haven't been able to discover a way to make an entire copy and I always end up having to create an entirely new TB account, manually re-create the desired directory structure, then copy the emails one folder at a time from the existing account into the appropriate folders of the new account.  This is a real time-consuming and error prone procedure.  How can I copy the entire account at once?