You receive stamps proportionally with the number of sent stamps. You send one envelope, you receive one.
In addition to this, everybody gets a few extra envelopes. This is needed to accept new members into the system. Imagine that there are only two members. You and me. You send to me and I send to you. You have one and I have one. We are even. But someone else wants to join. This person must send to someone. If this new person sends the envelope to you, you will have more stamps received then sent. So this is why every member gets a few extra envelopes.
At the beginning there were only a few members and they received even more extra stamps then members do now. This is also my case, I did receive more then I sent. I am still here and I will catch up with sending. Unfortunate some of those first members are no longer participating. Those exchanges have been registered and the senders also received stamps.
As this project grows, this will be less of an issue. It will be easier to accept new members when we are many. In this case, members will receive less extra envelopes.
