message-forbidden-properties

message-forbidden-properties is a variable defined in `message.el'.
Its value is

(field nil read-only nil invisible nil intangible nil mouse-face nil modification-hooks nil insert-in-front-hooks nil insert-behind-hooks nil point-entered nil point-left nil)

Documentation:
Property list of with properties forbidden in message buffers.
The values of the properties are ignored, only the property names are used.