RECYLE CABLE BOX

ATT emailed me after canceling the tv service to recycle the outdated cable box rather than to return it.  How do I know if ATT will later ask for proof that I recycled the unit?  Or if ATT will charge me for the unit since they didn't ask for proof that I recycled it?  ATT does some strange things after canceling a service, most of which I wasn't informed about until it was too late.