This is what the confirmation email says:

Dear MileageAddict,

Thanks for signing up to receive a $25 American Express(R)
Shop Small(SM) Gift Card, compliments of FedEx. Your
registration is being processed, and you will receive the
Gift Card in the mail. Please be on the lookout for a
plain white, standard-sized envelope with a return address
of Salt Lake City, UT, and an address header labeled
"Do Not Discard."