Join your Mac to a network account server
If you join your Mac to a network account server, you can use services such as contacts, calendar, mail, instant messaging, and more. You access these services using Contacts, Calendar, Mail, Messages and other apps on your Mac.
To make sure you join the appropriate server, ask your network account server administrator for assistance.
Connect to a network account server
On your Mac, choose Apple menu
in the sidebar. (You may need to scroll down.)Click Join next to Network account server on the right.
Click the Add button
, then enter an administrator name and password.Enter the fully qualified domain name of a network account server in the Server field or choose one from the Server list, then click OK.
To add another server connection, click the Add button
, then repeat step 4.You can join one or more network account servers.
Click Done.
If your computer name contains a hyphen (-), you might not be able to join a network account server. To check your computer name, and change it if necessary, use Sharing settings.
Choose Apple menu 
in the sidebar. (You may need to scroll down.)
Stop using a network account server
On your Mac, choose Apple menu
Click Edit next to Network Account Server on the right.
Select the server you want to stop using, then click the Remove button
.Click Stop Using Server, then click Done.
Monitor network account servers
On your Mac, choose Apple menu
On the right, note the colour of the dot to the right of Network Account Server. If you’re connected to more than one network server, click Edit to view the status of each server name in the list:
Green: The server connection is working.
Yellow: Your computer is waiting for a response from the server.
Red: Your computer isn’t connected to the server.
To use most network services, you need a user account on the server that provides the services. The server can have its own user accounts, or it can use network user accounts. On a network with multiple servers, all servers usually use the same network user accounts, which are provided by a network account server, sometimes called a directory server.