Rated 3 out of 5 stars

would like this to work but when I'm looking at a subfolder full of duplicates and am telling it to find duplicates based on sender, subject, and file size and it doesn't then I'm not sure what it's doing...no log file that I know of to see and no way to debug as far as I can tell. Guess I'll have to dig thru the js and hope to see what it's doing or not.

Update: Ok, maybe it is finding and deleting duplicates but the subfolder in which it's finding the duplicates never updates to show that the duplicates are gone. I can find the duplicates that were deleted in the Trash but when I go back to the subfolder where the duplicates were found they still show. Even Repairing the subfolder doesn't fix the issue, nor does a restart. This happened in TB 43 and now 52.

This review is for a previous version of the add-on (0.3.12). 

The extension uses Thunderbird facilities to move messages to the trash or to delete them. With the default action - move to trash - you can always see what was deleted by checking out the trash folder, as you've also noticed.

Now, about the dupes still showing in the source folder: I use standard Thunderbird facilities to move messages; if the folder from which a message was moved does not update, that is a Thunderbird bug. And I do know some of these exist, especially in IMAP rather than local folders. The thing is, I can't start sticking my head where it doesn't belong and try to mess with Thunderbird's core behavior - that's a recipe for even bigger trouble.