Although your machine will share Athena's user and group information, you can add local users and groups as well. To avoid conflicting with Athena, we recommend that you give local users and groups numerical IDs either less than 100 or greater than 32000, and names not currently used by Athena users or groups. Also, you'll have to add local user names to /etc/localusers if you want them to receive mail at your machine: