From the NannyMUD documentation

LAST CHANGE

2000-12-18

COMMAND

NAME
        echoall - write a string to everyone in the whole game


SYNTAX
	echoall 

DESCRIPTION
	The string is sent to all players in the game. This should be used with
	very great care, as it can confuse many people.


NOTE
	People have been demoted for mis-use of this.