Hi there,
Been using #thunderbird for some time and is far better than outlook.
I was going to open a feature request but can't find any option on github. Will like to see a remove empty directory feature where a user can scan for empty folders in email accounts or in a selected area, by right clicking and select an option and then simply move the empty folders to the bin. Very often when moving emails from Gmail or other providers, one would end up with empty folders which would have to manually be deleted.