Using offlineimap to sync IMAP servers

[Micah Anderson <micah@xxxxxxxxxx>]

Hi,

We are considering using offlineimap in a way that most people don't
use it for, and we are seeking advice to know if this is even
feasible. What we want to do is to have an IMAP store in one location,
and use offlineimap for each user to sync that store to a separate
IMAP store in a different location. 

Think of it as a glorified rsync. So why don't we use rsync? Well,
rsync is a one way mechanism, so we'd have to run it on both sides; it
doesn't take advantage of the fact that there are maildirs involved,
so it doesn't know message IDs, flags, offlineimap doesn't re-copy a
whole message if it is flagged differently, or if it is moved into
another folder. Rsync takes a long time to start up, it has to build
what it is going to sync, and then it does it, this seems like a lot
of unnecessary overhead.

Does it make sense to use offlineimap to do this? Will it scale? We
would have to run an instance of offlineimap for each user (which
might be a problem with 10k+ users). The other problem is that we'd
have to store the user's password infomration in their configuration
file, which is not ideal, but we could write courierauthdaemon ways
around this I think.

Thoughts?

micah