Postman

it took me a while to realize, but this is weird. my postman knows where i live. my mail doesn't have my picture on it, so why, when i was walking out of my apartment building did he say, "so you live in A3?" which i don't, i live in A4, but still that's across the hall and this was the first time talking to him. how does he know that i live on the first floor and within one apartment number of where i actually do?

he also waves to me when i ride my bike down the street...like, leans out of his mail truck so i see him.