Enable-builtin-messages
From FreeSpace Wiki
Enable builtin messages (Action operator) Turns the built in messages sent by command or pilots on Takes 0 or more arguments... If no arguments are supplied any ships not given individual silence orders will be able to send buiilt in messages. Command will also be unsilenced All: Name of ship to allow to talk.
Comments
Exact opposite of disable-builtin-messages, this SEXP allows the specified ships and/or sources to send builtin messages (enemy/hostile arrival, critical damage, traitor, etc.).