How to use a custom confirmation email instead of the default email provided by Klaviyo

Hi @yevheniia, welcome to the community!

This is an interesting use case, so let me see if I can help.  Just to setup the context, when you use the built-in Klaviyo double-optin confirmation in the List setting, the subscribers’ email isn’t added to the List until they click on the email confirmation.  When you switch to single-optin, the email is added to the List immediately. 

To emulate the way Klaviyo works for double-optin, you need to create your own custom profile property for each subscriber to track who has double-opted in (and who hasn’t) since by default, everyone will be added to the List since you’re disabling the double-optin in the List setting.

First, I would create a simple “Email Confirmation Flow” that’s triggered on a List Subscription.  Let’s call the List “Pre Confirmed” that it’s triggered on.  

Then, I would send an email with the pseudo double-optin message with a link or button that updates the users’ profile property for “double-optin = true” or something similar to that.  You can use the “Updated Profile from Link” functionality to do this in one click for the user that takes them to a confirmation (or thank you) page.

Example: 

{% update_property_link 'double-optin' 'true' 'yoursite.com/confirmed' %}

Next, I would create a Segment of all users that have the profile property where “double-option = true” and label that as “Subscribers.”  This means that as soon as someone confirms from the first Flow, they enter this Segment. Then you can create your Welcome Series Flow based on a “Segment Triggered” and select that Segment of “Subscribers.”

From here, you can create your normal sequence of email messages in your Welcome Series Flow.

You may also want to make sure your Campaign emails are only sent to those who has that property, and you may want to go back and update any current/past subscribers to make sure they have that property as well.  

Hope this helps get you started.  If any of the above isn’t clear, just let me know.