When message is archived it is located in Archive within directory named by year message belongs to.
If user has messages organized by directories, and user has set option to preserve directory structure in Archive, then, below year directory, directory is created and message stored there.
This is bit awkward as messages from the same directory are being scattered in separate directories for each year. Accessing those messages becomes impractical and hard to use.
I would suggest option to change way how things are handled. If message is located in sub-directory, then that sub-directory should be created in Archive and then year sub-directories created within that directory. That way, all messages form one directory stay in the same directory in Archive, but separated by year. That is much better way to store them for later use as they would be grouped in the same manner as in active part of database.