Initial mailbox sync and connection problems

[Gunter Ohrner]

Hi!

I'm currently trying to populate a new Maildir by duplicating the 
contents of an existing IMAP account using offlineimap 6.2.0.

Unfortunately, the running sync often terminates with offlineimap 
exceptions for various reasons. (Obvious connectivity problems as well 
as exceptions of which I do not know the exact reason.)

When restarted, offlineimap starts to copy a lot of the already 
downloaded mails back to the server, which a) causes tons of duplicates 
and b) will never let me finish the sync... :-/

Is there any way to make offlineimap correctly recognize the mails it 
already has downloaded to stop it from pushing the massages back to the 
server?

The server is running dovecot 1.0.15 from Debian Lenny.

Greetings,

  Gunter