I had mail redirected from one London address to another when I moved some years ago. I got mail, I thought it was working. But, as Kate D suggested, I was living in blissful ignorance. A couple of years after moving I got a call on my mobile (I'd had the same mobile number for donkey's years). It was from a Swiss couple I'd met and got friendly with when I was travelling in Bali after my first trip to NZ. We met and had a great 'catch up' and they told me that they had sent me an invitiation to their wedding - to my old address during the time I was paying for redirection :-(