Rated 5 out of 5 stars

This is very handy. I don't know why, but sometimes I get duplicate messages with my imap accounts. I have multiple clients that intermittantly sync with the server. One client has filters that move some messages to subfolders. I'm theorizing that this may be why I'm seeing dupes. But this add-on cleans them up.

I am on the beta channel and when I upgraded to 57.0b1 (32-bit) today, the process started, but the main window did not show up. Narrowed it down to this addon. I'm planning on reverting back to the release channel and if it continues to be a problem will report back.

5-stars because it works and if I am using the Beta version of TB, then I get what I pay for. ;-)

This review is for a previous version of the add-on (0.3.14). 

Working on it:
https://www.mozdev.org/bugs/show_bug.cgi?id=26429

... but it'll probably take me until the end of the month since I'm super-busy with other things.