Mozilla Mail client doesn't have offline error handling capability. That is if a problem occurs while synchronizing offline actions then it causes those messages to be lost. Eg: The destination folder of messages moved is deleted prior to synchrinization. Unable to move to a IMAP folder because the source messages have non-standard headers. Outlook Express handles such problesm by automatically creating a folder called "Offline errors" to stores the messages without causing them to get lost.

what happens if the destination folder is deleted? Do the source messages get deleted? Or if the source message have "non-standard headers"?

hopefully this is encompassed in current sync work, and SM doesn't have different issues from thunderbird

(In reply to comment #2) > hopefully this is encompassed in current sync work, and SM doesn't have > different issues from thunderbird well, yes; perhaps this should be moved to some component of MailNews Core (Database maybe?)

I'm not sure what you mean by "the current sync work", but if it's imap auto sync, that's just one way message body download and isn't related at all to this bug. I'm landing a separate fix that will prevent us from trying to playback moves to folders that don't exist, which should deal with the first example. For the second example, the move should just fail and we shouldn't delete the original, just like if you tried to move the message while online. This is not a database bug - it's really an IMAP bug, but our only imap component is networking, which I take to mean the imap networking code in the narrow sense. There was an offline component, but I think that might have been removed at some point.

yes, I meant offline/sync in the larger sense of what is being attempted for TB3. current description for SM mailnews: backend includes "offline"

I think I've fixed the various errors playing back move operations and handling failures on copy, so I'm marking this fixed.