I am currently running Zimbra 6.0.7_GA_2473.RHEL5.NETWORK on RedHat Enterprise 5.2 and have built a new server running Zimbra 7.1.4_GA_2555_NETWORK on RedHat Enterprise 6.2 to eventually replace the old server. I want to migrate the accounts to the new server in small groups and need to know what is the best method to accomplish this.