I'm glad someone bumped this. I sent postcards almost the entire first year, won a couple things, etc. Recently, I found a stash of old, already filled out cards so I started sending them again. Nothing changed, I have the proper additional postage, etc, but I got them ALL back, day after day, saying it was undeliverable, and unable to forward.

I stopped, assuming they had stopped the promo or something.
Any thoughts?