Why is my Welcome Series not sending?
If you're using Klaviyo signup forms to collect new subscribers, verify that these forms are pointing to the list that triggers your welcome series. You can do this by heading to the Signup Forms tab, finding your live forms, and clicking on the submit button.
Additionally, if you have newsletter signups synced through your ecommerce integration, head to the Integrations tab, toggle to Enabled Integrations, and find your ecommerce platform. Here, you will be able to see which list new signups are added to. This should match the list that is triggering your welcome series.
It's also important to verify if the list connected to your welcome series is double or single opt-in. By default, all Klaviyo lists are double opt-in, meaning new subscribers will have to confirm their subscription before they are added to a particular list and are eligible to trigger a welcome series.