Well, after a total of three messages from YOUDISCVERREWARDS.COM at the designated address, it stopped suddenly, and there have been no further messages received on it.

InterActiveCorp's legal department never called me back.

Maybe it was an inside job -- perhaps an employee of InterActiveCorp stole a bunch of subscriber e-mail addresses and tried a bit of spamming. Perhaps that person got shut down and discouraged from doing it anymore... Or fired -- that would be nice!