Using rsync to migrate from an previous ZCS mailstore to a fresh ZCS mailstore may be expected for multiple explanations: You'll need to disable the zimbraMailboxMoveSkipBlobs and zimbraMailboxMoveSkipHsmBlobs attributes around the source(NG) server just before initiating the account migration. Once the import is completed successfully, be sure to seek advice https://www.hostscheap.com/zimbra-migration-service