Using rsync to migrate from an old ZCS mailstore to a fresh ZCS mailstore is usually expected for various factors: After the accounts are migrated to Zimbra Daffodil (v10) server According to Migration of accounts segment, import the Cell knowledge using the migration utility: File /opt/zimbra/tmp/modules/backup/backup-data.tgz is going to be https://www.hostscheap.com/zimbra-migration-service