I've sent expired redemptions to Topps and I registered them via USPS.
Topps would mail them back and give you some letter saying they won't honor them since they have expired.
The only company that has given me a plus is Panini. I sent an expired redemption from 2005 recently and they actually redeemed since they was in their 'vault' plus gave me a bonus card for sending it.
Upper Deck on the other hand, I did the same thing, mailed an expired redemption and they sent it back with a letter and a pack of a 2010 brand of the same sport for trying to redeem it but they can't honor it also but they said, enjoy the pack! Of course, I pulled nothing but base singles.