Hello Varazdinec,
I don't think you completely understand how this works.
You receive an envelop from the Netherlands with a code because that is the code from the stamps that are send to you.
You are NOT supposed to use that code again. On your envelop. This code has already been used by the person who send you the stamps.
You use this code to register the stamps ypu received on this website. Then the person who send them to you can see that they are received and that person van send another bag to someone else.
When you want to send stamps to a person you go to the website click on "send stamps" and then you get YOUR code that you write on the envelop for the person you send to.
To be clear: you send stamps RANDOM
You don't send back to the person you receive from.
It can be possible that you get the address from someone who send to you. But that is not always the case.
I hope I made it clear for you.
