I tried the email just now and got this:
Carnival Corporation has engaged Stockperks to implement a more automated and streamlined process for the processing of shareholder benefits. During the ongoing transition phase, shareholders may be redirected to Stockperks to engage with our updated redemption process. Full details of how to submit your shareholder benefit claim can be found here: https://www.carnivalcorp.com/shareholder-information/shareholder-benefit.
The Stockperks service is governed by Stockperks’ Privacy Policy, Terms of Service, and may be subject to other Stockperks policies and terms. For information regarding Stockperks’ use and processing of your information, technical support, account setup, and all other questions regarding the use of Stockperks, please contact Stockperks at carnivalcorp@stockperks.com. For all other questions, please contact us at 1800-438-6744 ext 70450.
Sincerely,
Carnival Cruise Line
so I guess it's Stockperks. To bring it back to the OP...I have a casino rate and was denied through Stockperks..YMMV