Hey there. You may need to use another email address, verify your email on your Bungie.net account, then resend the Bungie Rewards email. Make sure to click "THIS LINK" when you receive the email. You may need to use a major email provider, such as Gmail or Outlook, to receive the email. Apple/iCloud emails seem to be blocking Bungie Reward emails at the moment.
Ok I've fixed it, i changed some notifications settings and then changed my email address. Sorted 😁