The first question is 'would it be sent today' or is it just accepted that employees have total overlap of private and working lives.
I think there would be anarchy if you could block phone calls as easily as you can Faceache/VP etc in the workplace.
I bet the memo was signed, 'Mr Cholmondley' with no job title because they all knew who he was, rather than 'Darren, Trainee Junior Assistant Manager of Memoranda, Human Resouces Division'