What are the little square boxes on Japanese envelopes/stationery?

Question:

I just recently bought some stationery from online and there's little square boxes on them. There's like 7 tiny little boxes and I was wondering if maybe they are used for postal codes or an address or something?

I can't really find any examples so here's a link to one of the letter sets I bought...
http://www.shopkawaii.com/Q-Lia-Little-Red-Riding-Hood-Fairy-Tale-Letter-Set-p/q-30155-7.htm

Thanks!

Answer:

Those boxes are used for Japanese postal codes which based on 7 numbers.
Bigger 3 boxes are for City code and following 4 smaller ones are for Town code, if I explain simply.