Isn’t it annoying when you’re waiting for an important letter and the postman never comes. Or he delivers a lot of bills and adverts but not the letter you want.
I accept that sometimes he has no letters for me. When that is the case, why can’t he ring the door bell and tell me he has no letters for me?
After all, when I check my computer it tells me there are no new messages on the server. So why can’t the postman?