Hello @ellen,

Welcome to the Klaviyo Community!

Great question! When you add members to a list via a .CSV, a double opt-in confirmation email is not triggered. 

Instead, if you already have a list of members you’re trying to import into your account and trigger the double opt-in email, I would suggest adding those members to a list using our List API. Specifically the Subscribe Profiles endpoint. 

Alternatively, since it sounds like these users may have provided implicit consent, you could also design your own email that simulates a double opt-in email asking if these users would like to confirm their subscription or unsubscribe. Remember to check with your local jurisdiction if this method is a viable one before actioning. 

I hope this helps!

David