The Additional Message on User Login Parameter
The option to display an additional message on user login allows you to inform the user that their actions are being monitored and also to notify them of corporate policies or the laws of the country.
If the Enable displaying of additional message checkbox is selected (on the Editing Client / Editing Client Group page, on the Authentication Options tab, in the Authentication Options section at the top) to enable this option, the Client will display an additional notification message to the user on login to Windows.
After the user confirms acknowledgement of the message, they will be allowed to log in.
For more information, see Enabling the Displaying of an Additional Message.