In Microsoft Exchange Server, the Exchange server on which a user’s mailbox content resides. A home server must have a private information store to contain mailbox contents, but it does not need to have a public information store. You can have many home servers in an Exchange organization.
You should dedicate specific servers as home servers in sites that have large numbers of users as well as to limit the number of home servers to streamline and simplify backup operations. Mailboxes can be moved between servers so that a user’s home server can be changed.