There's hints that it is, but apart from a computer and the odd phone and an old tv, that's about as 'modern' as it gets. It's a very rural game, with lots of little details that breathe life into this space (which you may not see straight away!) like cobwebs hidden under tables, or a wonky painting, left over pencil shavings around a ledger, weeds growing in through old brick work into the house, things like that.
How you run the post office is totally up to you also; you could even lock the door for the entire year and not let a single customer in! You could just spend the year farming, fishing or exploring the huge woods around the village. Obviously, your parents would hear about this upon their return and wouldn't be happy, but again, player choice is what I'm going after. Once you get those front door keys and you arrive at the village by train...you decide!
The family-employed postman 'Pete' has known you since you were a baby. He acts as your mentor upon arrival on New Year's Eve, and he'll collect the mail/parcels at 6am before you even wake up, but you can fire him at any time, having to hire someone else, or even cycling through town delivering them yourself and keeping the profits!
I'm going for a dynamic relationship system, where say, a villager who has become a bit of a celeb within the village comes in to order exotic ingredients every thursday, places his order and expects to come back next week to collect them. What's this? An awesome recipe that you've discovered that needs an exotic mushroom? I could choose to hunt for it myself...or...simply remove it from that guy's order...I could say it never arrived in the shipment!
And bingo; you've created a possible flux with that customer. You might get away with it once, maybe twice...but he might get suspicious and suprise you by coming in every day!

This is just one example of a dynamic relationship I hope to implement. I'm going for thirty villagers, with some really good personalities. That's not to say that the post office itself doesn't have a few unique things about it just waiting to be found...