--- title: "Send a signup confirmation email through Klaviyo" description: "Welcome customers the moment they join a back in stock waitlist, using STOQ's signup metric in Klaviyo." url: https://help.stoqapp.com/back-in-stock/klaviyo-signup-confirmation-emails/ product: "Back in Stock" section: "Klaviyo" last_updated: 2026-10-29 --- # Send a signup confirmation email through Klaviyo > Welcome customers the moment they join a back in stock waitlist, using STOQ's signup metric in Klaviyo. Every time a customer signs up for a back in stock alert, STOQ sends a signup metric to Klaviyo. You can build a Klaviyo flow on that metric to send an instant confirmation or welcome email, separate from the restock alert itself. ## Before you begin | Requirement | Detail | |---|---| | Klaviyo connected | Klaviyo must be connected to STOQ so the signup metric flows in. See [Sync back in stock signups to Klaviyo](https://help.stoqapp.com/back-in-stock/connect-klaviyo-for-back-in-stock/). | | The signup metric | The metric is **Customer signed up for alert (STOQ)** on an OAuth connection, or **Stoq - Customer signed up for alert** on a legacy API key connection. | ## Build the confirmation flow 1. **Create a flow in Klaviyo** In your [Klaviyo dashboard](https://www.klaviyo.com/flows), create a new flow and choose to build your own. 2. **Set the trigger to the signup metric** Set the flow trigger to the **Customer signed up for alert (STOQ)** metric (or the API-key equivalent). This can't be changed after the flow is created, so pick the right one. [Image: The Klaviyo Select a trigger panel for a Draft flow named flow, with the subtitle Profiles enter the flow when this happens and the tabs Recommended, Your metrics and All triggers where Your metrics is active, listing STOQ metrics including Back in stock alert (STOQ), Back in stock reminder 1 and 2, Back in stock SMS alert and reminders, Customer signed up for alert (STOQ), Preorder confirmed, Preorder payment failed, Preorder shipping update and Preorder SMS confirmed, beside an empty Trigger block reading Select a trigger; with markers: 1 on the Your metrics tab, 2 on the Customer signed up for alert (STOQ) metric row.](https://help.stoqapp.com/images/general/klaviyo-signup-confirmation-emails-1.png) 3. **Add an email action** Add an **Email** action and design your confirmation. Insert variables with Klaviyo syntax, for example `{{ event.product_title }}`, to name the product they signed up for. To link back to the product, use `{{ event.product_page_link }}` as a button URL. [Image: The Klaviyo Email details side panel for a Draft flow, showing the Email name field set to Email #1, a Status dropdown set to Draft, a Subject and sender section with a Subject line field reading Email #1 Subject, a Preview text field, an Edit sender button, and a Template section with a Select template button, next to the flow canvas where the Trigger reads When someone Customer signed up for al... feeding an Email #1 block with a Set up email button and Smart sending set to Draft at Day 0.](https://help.stoqapp.com/images/general/klaviyo-signup-confirmation-emails-2.png) 4. **Set the flow live** Change the flow status to **Live**. New signups now receive the confirmation. [Image: The Klaviyo flow canvas for a Draft flow named flow with the Actions panel on the left, showing the Trigger block reading When someone Customer signed up for al... feeding an Email #1 block with subject Email #1 Subject and Smart sending set to Draft at Day 0 leading to End, and the black Review and turn on button in the top right; with markers: 1 on the Review and turn on button.](https://help.stoqapp.com/images/general/klaviyo-signup-confirmation-emails-3.png) [Image: The Klaviyo Review and turn on side panel for the Draft flow, with a Preview flow card and a Preview button at the top, a Flow status section whose dropdown is set to Live with the radio option Update status now selected above a Schedule option, and Save and Cancel buttons at the bottom; with markers: 1 on the Live flow status dropdown, 2 on the Save button.](https://help.stoqapp.com/images/general/klaviyo-signup-confirmation-emails-4.png) ## What you can put in it Because the metric carries the product and customer details, a confirmation email can do more than confirm: recommend similar products, share a first-order discount, or set expectations for when the alert will arrive. See [Personalize Klaviyo back in stock emails](https://help.stoqapp.com/back-in-stock/customize-klaviyo-back-in-stock-variables/) for the full variable list. ## Check your setup Sign up for an alert on your storefront with a test email, then confirm the flow fires and the confirmation email arrives with the product name filled in. ## FAQ ### Is this the same as the restock alert? No. This fires on signup, the moment a customer joins the waitlist. The restock alert fires later, when the product is back. They're separate metrics and separate flows. ### A variable like the image is blank Some properties can be empty for a given signup, for example `image_url` when the product has no image. Check the product in Shopify, and confirm the property name matches the variable reference. ### The confirmation doesn't send right away If you use double opt-in, delivery can wait until the customer confirms. See [Set up double opt-in](https://help.stoqapp.com/back-in-stock/notify-me-double-opt-in/). ### I can't change the trigger metric A flow's trigger is fixed once created. If you picked the wrong metric, create a new flow with the correct one. ## Related guides - [Sync back in stock signups to Klaviyo](https://help.stoqapp.com/back-in-stock/connect-klaviyo-for-back-in-stock/): Connect Klaviyo and start receiving the signup metric. - [Personalize Klaviyo emails with variables](https://help.stoqapp.com/back-in-stock/customize-klaviyo-back-in-stock-variables/): The event properties available on the signup metric. - [Set up double opt-in](https://help.stoqapp.com/back-in-stock/notify-me-double-opt-in/): Require customers to confirm their signup.