[Bug 230699] New: dimap DATA LOSS when uploading changes is interrupted

[Reinhold Kainhofer]

https://bugs.kde.org/show_bug.cgi?id=230699

           Summary: dimap DATA LOSS when uploading changes is interrupted
           Product: kmail
           Version: unspecified
          Platform: Ubuntu Packages
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: NOR
         Component: general
        AssignedTo: kdepim-bugs at kde.org
        ReportedBy: reinhold at kainhofer.com


Version:            (using KDE 4.4.1)
OS:                Linux
Installed from:    Ubuntu Packages

KMail has a serious data loss problem with flaky internet connections. If the
upload of moved mails in a folder is interrupted for some reason (connection
breaks down, aborted manually, ...), the next mail check will purge the whole
dimap cache (including the mails that were moved to the folder and not yet
synced to the server!!!!) and re-download the folder from the server. As a
result, the moved messages will be removed on the server from the inbox, but
are never added to the new folder on the server... 

Steps to reproduce:
1) Take some large messages from the inbox on a dimap account
2) Move them to some other folder on the dimap account
3) Trigger a dimap sync of the whole account
4) The messages will be removed from the inbox on the server first.
5) While the sync is uploading the new messages to the new folder, disconnect
your internet connection (or even just abort the sync with the "-" button next
to the progress bar in KMail!)
6) Trigger another dimap sync. 

The dimap cache of the folder where the messages were moved to is purged
locally and all newly moved messages are simply discarded and only the messages
on the server are downloaded all over again. As a result, all messages that
were not uploaded before the connection broke down or the sync was interrupted
are GONE for good.

There are actually two problems here:
1) The serious problem is that an abortion of a dimap sync can make the dimap
cache invalid. KMail should always be able to keep a consistent dimap cache, no
matter what the connection status is.
2) KMail goes through the folders sequentially, first removing the mails from
the inbox. To prevent data loss, any sync operation should first do
non-destructive actions and only if they succeed go on with the destructive
actions... Apparently, KMail's sync of data as vital as mails does not do this.

Cheers,
Reinhold

-- 
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.