My wife received a post card as separate US Mail piece a day or two after the goods were on hand. It said that a 5-star review would be rewarded with a gift card. There was no wording that specifically encouraged that kind of review, but we certainly thought it was shady.

The post card had all sorts of Amazon logos and regalia. It has been destroyed.

Clearly this channel couldn’t be snooped by Amazon unless it provides the means for printing and sending the cards.