i'm currently in recovery from akonadi all of a sudden forgetting about all my local mails (see bug #345211 ). as i was trying to import those mails from backups and then moving the imported folder, some folders couldn't be moved, the error message read "unable to retrieve item from resource: invalid entry".

i investigated the problem and found that the error was triggered by certain mails in the respective folder which did not have a mail body any more, only the header was still there. in one folder this was the case for about 40 "normal" mails, while in all other folders this has exclusievly happened to unsubscribe confirmation mails from various mailing list servers. the mails were identifiable because kmail shows an error message in its status bar when selecting one of them. i was able to move all intact mails and then removing the folder containing only invalid mails.

the main question is where those empty mails came from. this was an archive with mails from the part 15 years, but the most disturbing finding (normal mails without body) were from around 2012-2014. it was all mails that were transfered by kmail from IMAP to a local maildir resource. the data loss most likely happened then.

Reproducible: Didn't try

Steps to Reproduce:
well, this is hard to reproduce. but you might be "lucky" if you manually remove mail bodies from a maildir archive, import the archive with kmail and then try to move the imported folder.

Actual Results:  
folder cannot be moved, a rather cryptic error message is shown. if broken mails are identified, they cannot be deleted -- you have to move all other mails  to another folder and then delete the folder containing the invalid mails.

Expected Results:  
at the very least, the error message should explain *why* you cannot move the folder. in addition, it shouldn't be such a painful excercise to identify the broken mails; kmail/akonadi should list the items in question. and once they're found, it should be possible to delete them.