Distributing Accounts Across Servers:
In an environment with multiple mailbox servers, the class of service is used to
assign a new account to a mailbox server. The COS Server Pool tab lists the
mailbox servers in your Zimbra environment. When you configure the COS,
you select which servers to add to the server pool. Within each pool of
servers, a random algorithm assigns new mailboxes to any available server.
Note: You can assign an account to a particular mailbox server when you
create an account in the New Account Wizard, Mail Server field. Uncheck
auto and enter the mailbox server in the Mail Server field.