The prerequisite to enabling archiving and discovery is the installation and configuration of the zimbra-archiving package
on at least one mailbox server. The installation of this package provides the ZCS discovery (also known as cross mailbox) search tool and sets the attributes that allow archiving to be enabled on the Zimbra MTAs.
To enable archiving and discovery, select the zimbra-store and zimbra-archiving packages during your installation process. The zimbra-core package is installed by default.
See the Zimbra Archiving and Discovery chapter in VMware Zimbra Collaboration Server (ZCS) Administrator’s Guide for more information about configuring and archiving.