I am testing a migration from Dovecot to ZCS using imapsync (1.456) which is actually going very well. My plan is to use imapsync to transfer all of the user data at one go, update DNS from old server to new, and job done.
My only point of concern is that when the email clients connects to the new server via IMAP for this first time, they download all the content again. I have tested this only with Outlook 2010 and Apple mail.app ( lion ).
I am just wondering if this is a normal side effect of this migration? If so I can live with it - I just have to advice the users of this so they do not panic when all of their mail vanishes when it is resynchronised with the server.
Or, If this is not normal, where would a good place be to start trouble shooting? I have already spend 3 days looking this this. Any suggestions would be welcome.