Hosted Exchange annoiences

Mike Kelly mike at
Wed Sep 11 21:42:14 BST 2013


I've been using offlineimap with Exchange with great success for about 2
years.  In that time my company migrated over to Hosted Exchange, which
is Microsoft's hosted Exchange product.  It still pretty much works as
before, except that now there are some extra annoyances.

First there is the UIDValidity issue. <conjecture>Probably mail is
stored on more than one back end server, and probably the UIDs are not
synchronized between these servers.  I suspect that periodically servers
are shut down for maintenance, and my account is switched from one
server to another, so I get all my mail with new UIDs.</conjecture>
This has happened twice in the last 6 months, and I've had to
re-download my mailboxes, which total over 4G in size, so it takes a
while, even with multiple connections.

I was wondering if anyone has considered an alternative to a wholesale
re-download, by simply requesting message-id headers and remapping the

The second issue with Hosted Exchange is that it seems to really hate
doing context switches between mailboxes.  Using the -o option on each
mailbox is much faster than the current behavior of downloading a few
messages from box A then a few from B, and A again, etc.  This happens
even though I'm using only one connection.  Have I missed the directive
which tells offlineimap to download from only one mailbox at a time?

To work around this slowness I tried to enable multiple connections,
which brings me to the third annoyance with Hosted Exchange.  Hosted
Exchange tends to get a little temperamental when multiple connections
are used, and will suddenly lock me out of my account for a while.
Offlineimap does not take this well and tries a few zero length reads
on a few different mailboxes before dieing with an ugly traceback.
I'm not actually sure what triggers this, but I'm happy to help debug

These problems are really problems outside of offlineimap's control,
but it would be nice to have a few settings to help work around the



--------Mike at

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