Postcard size question

[bunnyfoo]

I was talking to my friend who's also sending in postcards. She had an old copy of the rules ... the ones that said postcards were suppose to be 3x5. So that's what she's been sending in. I told her that USPS (and the contest) requires postcards to be 3.5x5. Anyway, she hasn't been getting the cards returned but she hasn't won anything either. So she was wondering if the post office was getting rid of cards or if they were making it to their destination. I guess there's no real way to know but I thought maybe someone here would have some insight I can pass along to her.

TIA