Review for Remove Duplicate Messages by Korwin
Rated 4 out of 5 stars
The extension does a good job of finding duplicate emails. There are many comparison criteria. The main drawback for me is the search results field is too narrow (680 pixels). I have 3440 pixels wide, and I can afford to examine the search results table in detail without having to guess the values of cropped cells or using horizontal scrolling. Especially when the number of found groups is several thousand.
To create your own collections, you must have a Mozilla Add-ons account.