1. A method for transmitting a message ( 611 ) in a mobile communication system ( 10 ) from an originating party ( 101 ) to a receiving mobile station ( 102 ), where a validity period ( 610 ) is associated with said message ( 611 ); characterised in the method comprising: transmitting both said message ( 611 ) and said associated validity period ( 610 ) to said receiving mobile station ( 102 ).