Review for Remove Duplicate Messages by Neville Hillyer
Rated 4 out of 5 stars
After contacting the author and getting an update for 'Deleted' (UK locale) I am now happy to use this extension.
I search on Message ID only and keep the largest at the review stage. Some size differences are trivial (eg extra header lines) but I have found that keeping anything other than the largest can result in the loss of attachments. It is not uncommon to receive two otherwise identical messages but with the attachment missing from one of them.
I use a pre-release version 0.3.4 from: www.mozdev.org/bugs/attachment.cgi?id=6300 which I have modified to remove "Set original message folder(s) for next duplicate search". Details at: www.mozdev.org/bugs/show_bug.cgi?id=22447
To create your own collections, you must have a Mozilla Add-ons account.