I'm just in the process to migrate our IMAP Accounts from SLOX 4.1 to Zimbra 4.5 using imapsync. Works great so far, but the the mailbox sizes differ extremely between SLOX and Zimbra, i.e. one SLOX account holds 2.1 GB - the same account after sync holds more than 8GB in Zimbra.

That makes no sense to me ... Any ideas?