Hi @eceaux,
Thanks for your reply.
Klaviyo cannot predicate an opt-in email send based on if a user is already a part of another list or not. Opt-in settings are either on or off for the list. However, there are a couple of other solutions.
The first solution is to disable double opt-in for the list entirely. For example, create a new list (Giveaway list), disable double opt-in for that list and add a pop-up or fly-out form to submit to that list.
If you do not want to disable double opt-in for this list, the another solution involves adding a button to an existing email that logs a custom property for that user. That solution would go something like the following: you configure a button on a campaign send to your Newsletter list with an option to sign-up for the giveaway. The user clicks the button which logs a custom property of “Yes”, I want to be a part of this giveaway. You create a segment based on that property: “properties about someone > a part of the giveaway = yes”, and you export this segment of folks and re-import them into your Giveaway list.
Thanks and have a great day.