Bug 340759

I will add unittest for it.
I don't know how it works but I need it.
I will investigate it.
Regards

 Bug 344227 - choosing to delete duplicates leaves copies mails of every duplicated mail (edit)

may be related. I will test whether deleting duplicates will delete all but one duplicate of each duplicated mail.

Strange, on testing to delete duplicates again with similar versions it now worked.

I still use KDEPIM 4.14.2. But I use akonadi server 1.13 branch from git except of 1.13.0-2 patches. I use c733429f4fa9696fb027ddc946e54f6bbb68deaf of 1.13 branch but it just contains some performance improvements I think.

Anyway, now on synthetically testing it for me it worked for maildirs.

KDEPIM 4.14.2 (Debian/Sid) does not remove duplicates for me. Sometimes, the progress bar will show some "progress", sometimes not even that. The effect on the folder is the same for both: none.

I should add, unlike the OP, I'm seeing this with IMAP(S), with Kmail set to "always download" the IMAP folder contents.

*** Bug 318233 has been marked as a duplicate of this bug. ***

I marked my old bug 318233 relating to duplicate mails as a duplicate of this one as it still referred Nepomuk and I am trying to close all my bug reports that still refer to Nepomuk, as Nepomuk is gone.

Also marking as confirmed as Christian sees this as well.

Mint 17.1 Ubuntu KDE Kmail 4.14.2. Sometimes don't delete duplicates. Delete, if do some duplicates with coping. But don't work with messages imported or reimported 2 or more times through other mail clients, duplicates appear from two import sessions in different time. Example of identical messages one of which cannot be deleted differ only at first row:

1)
From - Mon Sep 15 00:29:19 2014
X-Mozilla-Status: 0000
X-Mozilla-Status2: 00000000
X-Mozilla-Keys:                                                                                 
Delivered-To: ****@gmail.com
Received: by 10.220.109.2 with SMTP id h2csp160438vcp;
        Wed, 18 Dec 2013 14:12:57 -0800 (PST)
2)
From - Mon Sep 15 00:44:28 2014
X-Mozilla-Status: 0000
X-Mozilla-Status2: 00000000
X-Mozilla-Keys:                                                                                 
Delivered-To: ****@gmail.com
Received: by 10.220.109.2 with SMTP id h2csp160438vcp;
        Wed, 18 Dec 2013 14:12:57 -0800 (PST)

(In reply to Knube2015 from comment #9)
> Mint 17.1 Ubuntu KDE Kmail 4.14.2. Sometimes don't delete duplicates.
> Delete, if do some duplicates with coping. But don't work with messages
> imported or reimported 2 or more times through other mail clients,
> duplicates appear from two import sessions in different time. Example of
> identical messages one of which cannot be deleted differ only at first row:
> 
> 1)
> From - Mon Sep 15 00:29:19 2014
> X-Mozilla-Status: 0000
> X-Mozilla-Status2: 00000000
> X-Mozilla-Keys:                                                             
> 
> Delivered-To: ****@gmail.com
> Received: by 10.220.109.2 with SMTP id h2csp160438vcp;
>         Wed, 18 Dec 2013 14:12:57 -0800 (PST)
> 2)
> From - Mon Sep 15 00:44:28 2014
> X-Mozilla-Status: 0000
> X-Mozilla-Status2: 00000000
> X-Mozilla-Keys:                                                             
> 
> Delivered-To: ****@gmail.com
> Received: by 10.220.109.2 with SMTP id h2csp160438vcp;
>         Wed, 18 Dec 2013 14:12:57 -0800 (PST)

First line maybe TheBat timestamp when client receive it from server, some programs have such columns for mails.

Update:

After following the instructions outlined in [0] for clearing up the akonadi cache directory, it seems that choosing "delete duplicate mails" on an IMAP folder has the desired effect again.

N.B.: I've updated to akonadi 1.13.0-3 from Debian/Unstable in the meantime.

[0] https://bugs.kde.org/show_bug.cgi?id=341884

This bug has never been confirmed for a KDE PIM version that is based on KDE Frameworks (5.x). Those versions differ significantly from the old 4.x series. Therefore, I plan to close it in around two or three months. In the meantime, it is set to WAITINGFORINFO to give reporters the oportunity to check if it is still valid. As soon as someone confirms it for a recent version (at least 5.1, ideally even more recent), I'll gladly reopen it.

Please understand that we lack the manpower to triage bugs reported for versions almost two years beyond their end of life.

Deleting dupes works for me in 16.04 (Debian/Stretch).

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information as soon as possible and set the bug status as REPORTED. Due to regular bug tracker maintenance, if the bug is still in NEEDSINFO status with no change in 30 days, the bug will be closed as RESOLVED > WORKSFORME due to lack of needed information.

For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please set the bug status as REPORTED so that the KDE team knows that the bug is ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least 30 days. The bug is now closed as RESOLVED > WORKSFORME due to lack of needed information.

For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!