I have, in Thunderbird, by accident in a single move (unintended drag and drop) moved a number of the same-level subfolders containing archived sorted/categorised messages and ended up with all of the folders ending in successive subfolders to each other down the line (the last folder being sub-sub-sub......).
Does anyone know how I can undo this safely without loss - unless I am quite certain I will not risk changing anything. Basically (as a metaphor) it is a matter of moving inner onion-skins (with all sub-skins intact) out to be outer skins in separate onions.
create a new folder then start at the bottom of the subfolders and copy NOT MOVE, each one into the new folder working up the structure. When you are happy with the structure rename the old one to something else then rename the new one to what you want. Delete the old when happy.
Thanks TTT, I had something like that in mind as a possibility but was hoping to do the reversal of the error as easily as I made it.....(forever hoping for an easier way :) Oh, well, and so off to the tedium.