I once had a celeb send a pen with there name on it. They didn't add postage to my SASE. The post office stamped a Postage Due and filled in the blank for how much. The postal deliverer is supposed to collect that money when they deliver it. (I have heard people who have had this happen). My guy either didn't see this note or didn't feel like walking ot my door. But either way you will still receive it back. I've sent a lot of SASEs with 63 cents and still get them back even if cardboard is added. Good luck!

I'd say if the celebrity chooses to include cardboard, then its at their cost. You have included postage already so, and I think most celebrities would be nice enough to add the difference

you'll stil receive something but if postage isn't enough most celebs will pay for the rest of the postage

On my SASE's, I always put my own return address and one 63 cent stamp on the envelope. 63 Cents is just enough to ship the envelope with the photo, and nothing else - no cardboard, nothing. But let's say that someone replies, and encloses a piece of cardboard, which will increase the postal charge. Will I still receive the envelope, even though it does not have enough postage?