Found a few Email folders with duplicates (some in sub-folders) going back a long time. Just downloaded the add-on, restarted Thunderbird & ran the program. ONLY A FEW duplicates were found & copied to "Trash". Running the add-on again results in "No Duplicates found!" message. Restarted Thunderbird & ran add-on again. Same result. Restarted Thunderbird, compacted files & ran add-on again. Same result. Restarted Thunderbird, ran "Repair Folder" to the folder with duplicates & ran add-on again. Same result. What am I missing? Does the add-on need updating ??? TIA GaTech76