@emailguy - That’s strange, from what I can tell, the Double Opt-in or Single Opt-in is controlled at your List settings/preferences.  I believe Zapier uses the “Subscribe” Klaviyo API Endpoint which should respect your List configurations. 

In fact, Zapier states this in the sub-text of the Action Event. See here:
 

Are you sure you are adding users to the expected List with the correct settings?

Yes, I made sure to check that a few times. The part that is strange is that like I said it works for some zaps, but not for others, even if they are both referencing the exact same Klaviyo list. I wasn’t sure if others have had this issue or if it would be on Klaviyo side or Zapier side.

Hey @emailguy,

Thank you so much for coming to the Klaviyo Community for support on your Zapier integration. Happy to help.

With the updated Zapier V2 integration endpoint, the endpoint should automatically default to your Klaviyo list’s settings, like @retention shared above. Because this integration is created by Zapier and not by Klaviyo I would suggest double checking your Klaviyo integration set up in your Zapier account just to double check that every step has been completed correctly. Second, I would reach out to Zapier Support team from inside your Zapier account to have them help solve why the integration isn’t working consistently. 

I hope this helps get you on the right path to make the integration through Zapier work consistently for you! Thank you for being a member of the Klaviyo Community!

I used Zapier to link new entries in an Airtable base to Klaviyo. The goal is to auto-subscribe these contacts to our newsletter list in Klaviyo.

In our newsletter list, ‘Single Opt-in’ has been selected for ages, yet our customers receive an email to confirm their subscription to the newsletter.

I have no clue how to stop these confirmations from popping up.