In Global Configuraton Mode, type:
banner motd the #message of the day#
The first character after motd becomes the delimiter, which we use to set the start and end of the message. This example uses the hashtag # as the delimiter.
When a user tries to access the router they will see the message:
message of the day
Note that any character can be used as the delimiter, provided that it only appears at the start and end of the message.