Players are notified that the game will be going down for maintenance or any other reason via commands. There are a couple of command that we can use to display messages. One is a system message which only appear in chat and the other is a similar message that appears in a small dialogue window which displays the message for everyone to see players usually have to click a button in order to remove the message. The feature you are suggesting can be done it's usually up to the staff member to determine which command he/she wants to use, so it basically comes down to preference.