https://addons.mozilla.org/en-US/thunderbird/addon/manually-sort-folders

EagleMatt said

In the Thunderbird left pane, the various account folders are ordered vertically. How do I re-order them, e.g. such that I can make a selected account folder appears higher or lower in the list. Drag and Drop doesn't work as I thought it might... Thanks.

I have a simple way of having certain folders appear first. Adding a dot or dots in front of folder name. more dots = the higher the folder appears. Example these folders would appear like this. It's just a work around.

  .....paper folder
  ...zzz
  ...new folder
    .an old folder