When the MAC workstation boots up, iPrint checks the default printer to ensure that the workstation is using the latest iPrint Client. If necessary, a notification is launched to update the newer client. The notification provides you two options:
Update: Click Update for downloading the client and launch the installer for updating the client.
Later: Click Later five times after which the iPrint Client is forcefully downloaded on the workstation and client installer is launched
If the notifications are disabled on the client workstations, then the user can click the Check for Updates option from the tray menu.