[Bug 104956] dimap: sudden mail loss

[Rob Kaper]

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http://bugs.kde.org/show_bug.cgi?id=104956         




------- Additional Comments From webmaster horrorpops com  2006-06-28 22:16 -------
Anyone who next experiences this bug please check whether all data is still present locally (and if so, back up) before starting KMail/Kontact again. Perhaps check the IMAP account with a different client, not supporting DIMAP.

I've checked the IMAP RFC a few times and I think the loss of data does not occur before or during the crash but when KMail starts again with an incomplete index and then starts deleting/expunging all messages it doesn't know about. In the IMAP protocol messages are marked for deletion and then expunged. Clients should not obviously not remove actual data until explicitly receiving the expunge responses per message and servers should not expunge messages not explicitly communicated to be. Neither would make sense to happen for to-be-kept messages during synchronisation even in the case of a crash and/or network failure. However Kmail expunging the messages (and only then delete them locally upon success) starting with an incomplete index would cause the deletion.

If not useful for locating the bug, checking the actual state of the data locally and on the server might prevent data loss for users experiencing it, or enable them to backup and restore.

I cannot explain this problem at all unless at some point KMail trusts a list of messages to be kept (presumably the index) instead of a list of messages to be deleted and then imposes that trust on the server.  I recommend someone check if this could indeed occur and then make sure DIMAP only relies on an explicit deletion list instead. This might turn out to be a large change, but from a design perspective anything else means asking for problems.

(I swear, if I find the time I'll just have to get back to KDE development.)