For me, any discount codes for Visa or Mastercard gift cards at giftcards.com did not prevent me from getting eshopping miles in the past, regardless of they are posted on eshopping or not.

For Visa or Mastercard giftcards, I just use them to buy costco cash cards or pay insurance, medical bills since they often allow partial multiple payments. I'll try to use them up as soon as possible usually within a month or so. I am pretty sure visa or mastercard companies are betting that we won't use them up right away, which gives them free funds to earn interest on.