protip: don't delete receipts.
most email storage these days is so ridiculously huge, there's no reason to delete those emails. make a folder for them (Playstation receipts, Steam receipts, etc).
that said, physical media is on it's way out. i'd be surprised if the next gen of systems is even offered with a disc drive. at this point, most games are way more data than a Blu-Ray can hold.