评分2星,满分5星

It does something but doesn't seem to accomplish anything on Thunderbird 68.2.2. Only the right-click menu item shows, but there are no preferences. When I select it from the right-click menu, the result is a popup that says "Could not find any duplicate messages in the selected folders.".

Edit 1:
The other clones of RD plugin in earlier versions of TB did find duplicates in the same circumstances. Also the preferences do NOT appear in Thunderbird Menu > Add-ons and Tools > Add-on Preferences
If that helps, I am using TB for Mac.

Edit 2:
The add-on preferences don't show neither in Add-on Preferences, nor in the Add-ons pane.
Also in my config there are leftovers from the original add-on from the time it was using it with an earlier version of TB, so in fact I do have saved preferences. These are not taken into count.

Last but not least, thanks for trying to help.

这个评论是针对附加组件的一个早期版本的(1.5)。 

So you have no duplicates, the preferences are in Thunderbird Menu > Add-ons and Tools > Add-on Preferences.

Edit:
The prefs are in 2 places:
Thunderbird Menu > Add-ons
Menu Bar > Tools > Add-on Preferences

If you can't change the prefs, you don't know what you're comparing.
I don't have Mac right now, so I can't test it myself.