Confused!

I was pleasantly surprised to receive 3 official cards in the post this morning, as I had already received more cards than I had sent. I am really not sure how this works - why I should have a surplus, when other people haven't even received their quota yet. Have I been lucky in the people, which have downloaded my address. Not that I am complaining, it is lovely to have recieved so many cards. Off to the post office today to send off another 5 cards.