win10 1803 was available without problems in TBver60 Rated 5 out of 5 stars

I was saved by this plug-in saving my time.
Recently, it became TBver 60.0 b 6 and it could not be used
Because it was painful, self-responsibility, but were available to change the ".rdf".
It is use in win10 1803.
I carried out the mail about 20,000, but it ended before I finished writing this review.
Since multiple folders are also distinguished more precisely than each folder, they are always being rescued.
Thank you.

it's not a real alternative to the original from Thorsten W. Schmidt Rated 2 out of 5 stars

I played a lot with the settings and unfortunately I found still a lot mails as duplicate. They were the same, not attachements. Quite easy to find them even by eye. No idea why the settings don't work.

In some setting-cases the JavaScript stopped the work. Maybe it's my big postbox with ~10.000 mails (there are surely and easily much bigger possible) which is merged by some postbox versions which lead to duplicates or quadruplicates.

Then I tried the xpi-addin from Thorsten (which is warned as not compatible to current Thunderbird version). It serves more information and it's much more precise - AND it found all duplicates. Unfortunately you cannot resize the windows.

So my recommendation is - ask for the code of Thorsten and recode it for current thunderbird versions.

Doesnt work for me Rated 1 out of 5 stars

Window opens that shows duplicate pairs, allows me to pick first/last. When I press OK to permanently delete, nothing happens.

Please file a bug

I think this is a known regression forc esome recent, but not super-recent, TB versions.

Essential! Rated 5 out of 5 stars

I don't know what I would do without this!
The only improvement that would be really good is the option to "Keep" (prioritise) messages that have been replied to. That way they could remain part of a long discussion thread & not break in the middle if I've chosen the wrong one.
How do I give you money? (No PayPal link on the Add-ons page).

This user has a previous review of this add-on.

Could use more settings Rated 3 out of 5 stars

I wanted to cull out some RSS element based on their website ('content-base' header), but unfortunately that extension does not offers this as a criteria for fiding dups.

So file a feature request

Nobody's requested this before; file a feature request and we'll see.

... having said that, Thunderbird might not be exposing this to me anyway.

Excellent! Rated 5 out of 5 stars

Handled thousands of duplicates without problems. Thanks!

Could not have been a better fit Rated 5 out of 5 stars

Didn't know how to use it. So I tried right clicking on a folder, and well there it is! It just works, and has exactly the right options. Went through 4000 messages in <1 minute, even when set to compare the message bodies. It displays a summary of the messages it found, grouped together. It lets you compare them. It lets you delete permanently or put in the recycle bin. Just perfect, thank you!

This review is for a previous version of the add-on (0.3.15). 

Pay Attention to Search Settings Rated 5 out of 5 stars

At first this app seemed to not work. I get dupes intentionally because I have gmail also reading my main mail account, partly to have a backup on another server, partly as a defense again false positive spam blocking. By changing the default setting to be only Author, Message ID, Sent Time, and Subject, it properly removes my dupes. Unlike another app for dupe reduction, this app does not leave my keyboard delete key disabled after running it. Your mileage may vary.

This review is for a previous version of the add-on (0.3.15). 

No duplicates ...? Rated 1 out of 5 stars

I suppose it might be a decent set of coding but it finds no dupes in my sent folder. Unchecked the selection in the dialog box. They're clearly there. Does not work.
Thanks for the reply Eyal. On my installation the dialog box looks nothing like the one depicted on the linked page. I'd post you a picture but I don't think this is the right forum for even this type of conversation. As I said earlier, I have unchecked Skip Special Folders (Sent ...)--there is no selection for a positive "search special folders", only a Skip selection to be unchecked--and left all other check boxes checked. I don't know why I get duplicated messages in my Sent folder but, regardless, there are two of everything so it seems the application should not report that there are none. I'm perplexed.

This review is for a previous version of the add-on (0.3.15). 

Special folders are not searched by default. Also...

You need to make sure to set the appropriate comparison criteria. If you were to compare your sent messages by send time, obviously there would be no duplicates since you don't send different messages at the same time.

And again - you'll need to enable searching special folders.

Nicht alle Duplikate werden gefunden Rated 3 out of 5 stars

Leider werden nicht alle doppelten Mails gefunden. Ich habe verschiedene Einstellungen ausprobiert. Mir ist es nicht gelungen alle doppelten Mails zu löschen.

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

Energy saver! Rated 5 out of 5 stars

Sometimes, I have been receiving the same emails from one of my accounts. (T-T)
But I don't know that phenomena now.
By good luck, This program makes duplicate messages removed easily. (^^)

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

When a version for 58 ? Rated 5 out of 5 stars

Very hepfull. But it is a great lack having no version for thunderbird 58.
May we hope it soon ?

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

Soon, I hope

I'll find time soon to work on compatibility with v58.

Sorry, I did not use it properly Rated 5 out of 5 stars

I had a problem scanning my mails in different accounts ( and The solution is to select one account and then CTRL + mouse click on the second account (or/ and third...). It finds the emails that were sent to both accounts.
Thanks a lot for this extension which saves a lot of time and seems to be quite safe for the user. Sorry I had to give it a bad appreciation before to get in touch with Eyal Rosenberg. I'll try to remove it.

This review is for a previous version of the add-on (0.3.14).  This user has 2 previous reviews of this add-on.

Great and helpfull add-on Rated 5 out of 5 stars

Really improved original add-on. Recommended - it works well.

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

This is a very helpful add-on. I do have a problem with it with 57.0b1 (32-bit), but that may not be add-on's fault. 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). 

About 57.0b1

Working on it:

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

fabulous and absolutely necessary add-on Rated 5 out of 5 stars

I just downloaded this and used it to fix a large Sent folder and another Sent subfolder which had been corrupted with duplicates and was slowing Thunderbird. As long as you don't overwhelm the Remove Dup Messages add-on with a huge number of sets (duplicates) it is great and reliable.
I found that it still worked on 40,000 messages with 14,000 duplicate sets.
Great Add-on

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

Thank you + limits

I've tested the extension with over 90,000 messages, but not as many dupe sets as you had. Good to know :-)

Also - readers should be reminded that if you include message bodies as a comparison criteria the extension would be much slower (although it should still get through them eventually).

Attention à la coche "comparer les adresses simplifiées et triées" Rated 4 out of 5 stars

Après de nombreux essais peu concluant, je viens de découvrir que si je décoche la case "comparer les adresses simplifiées et triées", le module fonctionne enfin correctement...
Auparavant, une fois sur deux elle partait en loop interminable, avec des messages de windows au sujet de script, et l'application ne répondant plus..
il doit y avoir un bug avec cette coche, donc je ne comprends par ailleurs par très bien l'utilité? C'est quoi une adresse "triés"?

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

Much slower than the original Rated 3 out of 5 stars

EDIT: breaks for some cases with large folders / large messages. (Plugin will hang, and TBird must be killed.) Also gets confused by differences in some client-side headers (X-Antispam, in my case). For now, I'm using a combination of this version and the original Remove Duplicates, in order to work around these problems.

Will update this review when I have more info.

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

I'm not dead yet...

Abandoned? Not really... I'm releasing a new version soon actually (no major changes, mind you). You should try actually talking to people or having a look at the Bugzilla before declaring thing to be abandoned. Please consider retracting that.

Anyway, about the "taking a long time" experience - I haven't gotten such complaints. Can you open an issue at so we can get to the bottom of this?

Performs the job smoothly and accurately Rated 5 out of 5 stars

Works smoothly and accurately. Some messages may not be defined as dupes because of the Compare Size option. Playing aroung with settings makes good result to avoid wrong removing!

Hey Eyal,

Sorry for my previous review :)
Do you plan further extention development?
Why there are duplicate messages which look absolutely the same, but one of them has the size =0 Which one I should consider to keep?


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

You're ignoring the comparison criteria

The extension supports a wide customizable range of comparison criteria; the messages you want to define as dupes are (almost certainly) actually different somehow: Different second of arrival; extra newline; different order of recipieints; etc.

It is actually a safety feature that, by default, the comparison is very strict. I'm sure you'll agree it's better to fail to delete some dupes, by mistake, than to delete non-dupes, by mistake. When you set the appropriate criteria you get the result you want.

Un bon programme et beaucoup de progrès : A encourager ! Rated 5 out of 5 stars

Dommage que ce programme ne soit pas une fonction initiale de thunderbird tellement il est utile.
Testé sur : thunderbird portable 52.2.1 (x32).
fonctionne très bien pour ma part.
Régulièrement et à cause de mes paramétrage de transfert / copie selon mes filtres mis en place dans thunderbird et Gmail ou autres provider pour lesquels je ne peux rien faire mieux j’ai 90 % des messages en doubles.

Vive cet addon !

Pour un réglage permettant de réellement effacer uniquement les messages en doublons, pour que tout fonctionne à la perfection, je conseille de cocher ainsi :
- Comparer les adresse simplifiées et triées
- expéditeurs
- Destinataires
- Date d'envois
- Sujet

Si vous coché autre chose, vous ne pourrez pas supprimer correctement les messages en doublons.

Faites ces réglages précis avant de croire que le programme fonctionne mal : cet addon fonctionne très bien une fois les paramétrages fait.

Bonne continuation

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

About the choice of comparison criteria

First - think your, Olivier, for the compliments. I'm glad you found removedupes useful.

About the choice of comparison criteria: I don't think there is a real single "correct" choice. I set the default to be rather conservative: It's better for people to fail to remove some duplicates than to remove too much by mistake. At the same time I have made the criteria easily accessible on the drop down menu so you can experiment and find the right combination for you. I feel it is a reasonable combination; but I am open to be convinced otherwise if you believe I should change the default. You can email me about it you like.