unsent means the warranty not in place?
if we want to send in, need receipt and date of purchase or not?
As with most warranty conditions, they request for proof of purchase before servicing (not when sending in the card), but will often honor the warranty even if such proof is not presented. In this case, since you have the original undated warranty card, you can send in the card whenever you feel like. (I wouldn't wait too long though) The warranty is only 1 year so it would have expired anyway so you have nothing to lose by trying.