Offlineimap erroneously deletes 10,000 emails

Sebastian Spaeth Sebastian at
Thu May 19 21:31:10 BST 2011

On Thu, 19 May 2011 21:55:33 +0200, Johannes Stezenbach <js at> wrote:
> Normally, if the UIDs on the server change (e.g. because the admin
> has moved your mails to another server), the idea is that the
> UIDVALIDITY changes, too.  Then offlineimap can detect this
> condition and will abort (isuidvalidityok() returns false),
> so that you have a chance to move your local mails out of the way.
> If the UIDs on the server all change but UIDVALIDITY does not, then
> in the best case offlineimap will delete all mails locally and
> will download them again with new UID.  However, if the new and
> old UID ranges overlap then the offlineimap sync process might
> actually lose mails.
> Thus:
> 1. check if the UIDs have changed on the server
> 2. check the UIDVALIDITY has not changed on the server
> 3. if both are true, complain to your server admin

Yep, good suggestions. Unfortunately, they require some IMAP internal
knowledge. OfflineImap should e.g. provide a debug output where it lists
the UIDVALIDITY values for all folders, so that you don't have to telnet
into your IMAP server.

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