Offlineimap erroneously deletes 10,000 emails

[Edward Z. Yang]

Sean,

I'm quite sympathetic to your concerns (I've had offlineimap do bad
things to my mail too), but quite frankly, it's not sensible to complain
about bugs in a version of offlineimap that has since had two bugfix
releases.  Upgrade and instrument.

Cheers,
Edward

Excerpts from seanh's message of Thu May 19 08:36:46 -0400 2011:
> Hey, so I was running offlineimap (version 6.2.0 on OS X,from macports)
> recently and I saw this:
> 
> Deleting 9810 messages (...) in Maildir [Archive], LocalStatus[Archive]
> 
> where the (...) was the identifiers of 9810 messages, i.e. the entire
> contents of my Archive folder containing several years worth of archived
> personal emails. Fortunately I killed offlineimap after it had managed
> to delete only a couple of thousand emails, and before it had synced
> this change up to the IMAP server and deleted the emails from the server
> as well (which would have lost them completely).
> 
> This is not the first time that offlineimap has done this to me, it's
> just the first time that I've caught it in the act. A few times over the
> years, when using offlineimap I've noticed dozens or hundreds of emails
> have mysteriously gone missing from my maildirs and from the IMAP
> server.
> 
> Offlineimap apparently believed that all of the messages in the Archive
> folder had been deleted from the IMAP server so it was syncing this
> change to the local mailbox. But the messages had not been deleted from
> the server, and I confirmed this (after killing the offlineimap process)
> by connecting to the IMAP server using mutt and opening the Archive
> folder, which still contains 9810 messages.
> 
> If I hadn't happened to have been looking at the offlineimap window when
> this happened (or if, say, offlineimap was being run by cron) then it
> would have deleted the 9810 messages from the local maildir and then on
> the next automatic sync a few minutes later it would have sent the same
> change back up to the IMAP server and deleted the messages from the
> server, losing them forever.
> 
> Is this a bug in the offlineimap code? Or a bug in offlineimap's sync
> algorithm? Was there a glitch in the IMAP server that caused it to
> momentarily report the contents of the Archive folder as empty and
> trigger a catastrophic response from offlineimap? Is there a safe way to
> use offlineimap so that I can be protected from losing mail in events
> like this?
> 
> Reading local maildirs with mutt is my preferred way to check my mail
> and offlineimap is the best/the only way to sync my IMAP accounts
> locally. But having seen this, I may have to give offlineimap up. I
> can't trust it not to wipe out all my email in one sudden, unexpected
> mass-delete.
>