thanks to everyone for their advice! i hadn't made the final payment yet... glad that was pointed out for future reference!
I forwarded the email to my TA who was able to get the discount for my cabin but not anyone else's (i was the only one who got the promotion email... seems to be a perk of being a "captain's circle" member)
since i got a mini suite, however, the total savings amounted to $1600 which will instead go towards excursions for my wedding guests! yay!