I’m trying to implement a newsletter signup. User enters their email and if they want to be on the marketing list or the build announcments list.  The way I have this setup in sendgrid is via a custom field request should be something like:

{

   “email”: “john.doe@appleseed.com”,

   “list”: “marketing”

}

Right now I can easily collect boolean values for if the user wants marketing or build announcments but I can’t see a way to transform that into the correct string to insert in the body. Thanks!