Setup Requirements For Adding a Mailbox Server The new machine you are adding must have the same operating system, including the latest version and patch levels, as installed on the Zimbra single server. The system clock must be configured with the same time on both machines. You must install the same version of the ZCS software that is installed on the single server node. A copy of the ZCS license needs to be added to a directory on the new machine. If you are adding Zimbra Proxy to ZCS, this should be installed on the existing single-server before you set up the new mailbox server. See the Multi-server Installation chapter, Installing zimbra-proxy section.
