Articles on: Integrations

How to fix back in stock emails not sending in Klaviyo after flow verification in STOQ

You have connected Klaviyo to STOQ, verified your flow, and everything looks green — but customers still are not receiving back in stock emails. This is a common issue that usually comes down to one of three causes: Klaviyo's Smart Sending feature is suppressing emails, a catalog item variable in your Klaviyo email template is blocking delivery, or the flow is using the wrong metric trigger. This article walks you through each cause and how to fix it so your Klaviyo back in stock emails start reaching customers again.


Cause 1: Smart Sending Is Enabled


Smart Sending is a Klaviyo feature that prevents a customer from receiving more than one email within a set time window (default is 16 hours). If a customer recently received any email from your Klaviyo account — such as a promotional campaign, a welcome flow, or an abandoned cart email — Klaviyo will silently skip the back in stock alert for that customer.


This means a customer who signed up for a restock notification may never get the email, even though STOQ successfully triggered the event and the flow ran.


How to Check if Smart Sending Is the Problem


  1. Open your Klaviyo dashboard and go to Flows.
  2. Click on your STOQ back in stock flow (e.g., STOQ - Back in stock alert (STOQ)).
  3. Click on the Email action block inside the flow.
  4. Look for the Skip recently emailed profiles toggle in the email action settings.
  5. If Smart Sending is enabled, this is likely suppressing your back in stock alerts.


How to Fix It


  1. In the email action settings, *turn off Skip recently emailed profiles for this flow.
  2. Click Save to apply the change.


Tip: STOQ's automatic setup already disables Smart Sending on flows it creates. This issue typically occurs when the flow was created manually or when the Smart Sending setting was changed after setup.


Back in stock alerts are time-sensitive and explicitly requested by the customer. Disabling Smart Sending for these flows ensures every subscriber receives their notification regardless of recent email activity.


Cause 2: Catalog Item Is Unavailable in Your Email Template


Klaviyo has a Catalog Lookup feature that lets you pull product data (image, title, price, URL) directly from your Shopify catalog into an email template. If your Klaviyo email template uses a Catalog Lookup block or catalog variables instead of STOQ's event variables, the email may fail to render or silently not send.


This happens because STOQ sends product data as event properties (e.g., {{ event.product_title }}, {{ event.image_url }}, {{ event.checkout_link }}). These variables are populated by STOQ at the time the event fires. However, if your email template references catalog variables (e.g., {{ catalog_item.title }} or uses a Catalog Lookup block), Klaviyo tries to look up the product in your synced Shopify catalog — and if the item is out of stock, discontinued, or not synced, the lookup fails and the email is skipped.


How to Check if This Is the Problem


First, confirm that Klaviyo is skipping emails due to a catalog item error:


  1. In your Klaviyo dashboard, go to Flows and open your STOQ back in stock flow.
  2. Click on the Email action block inside the flow.
  3. Go to the Recipient activity tab.
  4. In the left sidebar, click Skipped. If you see a count next to it (e.g., "Skipped (93)"), emails are being skipped.
  5. Check the dropdown filter at the top — if it shows "Skipped: Catalog Item Unavailable" with a count, this confirms the problem.


Next, inspect the email template to find the catalog references:


  1. Go back to the flow and click the Email action block.
  2. Click Edit Email (or Edit Template) to open the email template editor.
  3. Look for any Catalog Lookup blocks, or variables like {{ catalog_item.title }}, {{ catalog_item.image }}, or {{ catalog_item.url }} in the template content.
  4. If you find any catalog references, these are the cause of the "Catalog Item Unavailable" skips.


How to Fix It


Replace all catalog-based variables with STOQ's event variables. STOQ sends the following properties with every back in stock event:


Event Variable

Description

{{ event.product_title }}

Product name

{{ event.variant_title }}

Variant name (e.g., "Medium / Blue")

{{ event.title_incl_variant }}

Combined product and variant name

{{ event.image_url }}

Product image URL

{{ event.price }}

Product price

{{ event.currency }}

Currency code (e.g., USD)

{{ event.vendor }}

Product vendor/brand name

{{ event.product_id }}

Shopify product ID

{{ event.variant_id }}

Shopify variant ID

{{ event.market_id }}

Shopify market ID (for international markets)

{{ event.product_handle }}

Product handle/slug used in URLs

{{ event.checkout_link }}

Direct checkout link with product pre-added

{{ event.product_page_link }}

Link to the product page

{{ event.unsubscribe_link }}

Unsubscribe link for opting out of future alerts

{{ event.shop_name }}

Your store's display name

{{ event.shop_logo_url }}

Your store's logo URL

{{ event.shop_domain }}

Your Shopify store domain

{{ event.customer_name }}

Customer's name

{{ event.customer_email }}

Customer's email address

{{ event.customer_locale }}

Customer's locale/language preference


For the full list of variables including SMS and preorder variables, see Back in stock variables and Preorder variables.


To update your template:


  1. In the Klaviyo email editor, remove any Catalog Lookup blocks.
  2. Replace catalog variables with the corresponding STOQ event variables from the table above.
  3. For example, replace {{ catalog_item.title }} with {{ event.product_title }} and {{ catalog_item.image }} with {{ event.image_url }}.
  4. Save the template.



Tip: You can send a test event from STOQ to verify your template renders correctly. Go to Back in stock alerts → Settings → Notifications, open the Klaviyo flow section, and click Send test event. Then check the email preview in Klaviyo.


Cause 3: Incorrect Flow Trigger — Using Klaviyo Metrics Instead of STOQ Metrics


Each Klaviyo flow needs a metric trigger — the event that starts the flow. STOQ creates its own custom metrics to trigger flows. If your flow is using a Klaviyo-native metric (like Klaviyo's built-in "Back in Stock" metric) instead of STOQ's metric, the flow will never fire because STOQ does not send events to Klaviyo's native metrics.


STOQ uses the following metric names depending on how your account is connected:


Alert Type

OAuth Connection Metric

API Key Connection Metric

Back in stock alert

Back in stock alert (STOQ)

Stoq - Back In Stock Alert

Back in stock reminder

Back in stock reminder 1 (STOQ)

Stoq - Back In Stock Reminder 1


How to Check if This Is the Problem


  1. In your Klaviyo dashboard, go to Flows and open your STOQ back in stock flow.
  2. Click on the flow trigger (the top block that says what starts the flow).
  3. Check which metric is selected as the trigger.
  4. If it shows a Klaviyo-native metric like "Back in Stock" (without "STOQ" or "Stoq" in the name), this is the problem.



How to Fix It


Klaviyo does not allow you to change the trigger metric on an existing flow. You will need to delete the incorrect flow and create a new one with the correct STOQ metric.


  1. In your Klaviyo dashboard, go to Flows.
  2. Find the flow that is using the wrong metric and delete it (or set it to Draft so it does not conflict).
  3. Create a new flow or let STOQ create one for you:
  • Option A — Automatic setup (recommended): Go to Back in stock alerts → Settings → Notifications in STOQ. Open the Klaviyo section, click Reset setup, then choose Automatic setup. STOQ will create new flows with the correct metrics, templates, and settings.
  • Option B — Manual setup: Create a new flow in Klaviyo. When setting the trigger, select the correct STOQ metric:
    • If connected via OAuth: Back in stock alert (STOQ)
    • If connected via API key: Stoq - Back In Stock Alert
  1. If you used manual setup, go back to STOQ: navigate to Back in stock alerts → Settings → Notifications.
  2. Enter the new flow name and click Verify flow to confirm the connection.



Tip: You can check which connection method you are using in STOQ under Back in stock alerts → Settings → Notifications. If you see a Connected badge next to the Klaviyo section, you are using OAuth. If you see a field for a private API key, you are using the API key method.


How to Tell Which Metric Is Correct


The easiest way to confirm the right metric name is to look in STOQ:


  1. Go to Back in stock alerts → Settings → Notifications.
  2. Open the Klaviyo flow settings.
  3. The instruction text will tell you: "Select this event to trigger your flow: {metric name}" — this is the exact metric your flow trigger must use.



Troubleshooting


Symptom

Likely Cause

Fix

Flow is verified in STOQ but no emails are received

Smart Sending is suppressing them

Disable Smart Sending on the email action in Klaviyo

Email template shows blank product info or fails to render

Catalog Lookup variables used instead of event variables

Replace catalog_item references with event variables (see table above)

Flow never triggers even after inventory update

Wrong metric is set as the flow trigger

Delete the flow and recreate it with the correct STOQ metric (e.g., "Back in stock alert (STOQ)"), or use STOQ's automatic setup

Flow verified but shows "Flow not configured correctly" after re-verification

Flow name in STOQ does not match the flow name in Klaviyo

Ensure the flow name entered in STOQ matches the exact name of the flow in your Klaviyo dashboard

Test event sent successfully but no email received

Flow status is set to Draft or Manual in Klaviyo

Set the flow status to Live in your Klaviyo dashboard

Emails stopped working after reconnecting Klaviyo

Metric names changed after switching between OAuth and API key

Delete the old flow and recreate it with the new metric name, or use STOQ's automatic setup to regenerate flows


FAQs


Q: Why does STOQ show the flow as verified if emails are not sending?

A: STOQ verifies that a flow with the correct name exists in your Klaviyo account. It does not check the internal configuration of the flow — such as Smart Sending settings, template content, or whether the trigger metric is correct. Verification confirms the flow exists, not that it is fully configured to send.


Q: What is the difference between STOQ metrics and Klaviyo's native "Back in Stock" metric?

A: Klaviyo has its own built-in Back in Stock feature with a native metric. STOQ uses its own custom metrics (e.g., "Back in stock alert (STOQ)") to trigger flows. These are separate — STOQ sends events only to its own metrics. If your flow uses Klaviyo's native metric, it will never receive events from STOQ.


Q: Should I use automatic or manual setup for Klaviyo flows?

A: Automatic setup is recommended. STOQ will create the metrics, templates, and flows for you with the correct configuration — including Smart Sending disabled. Manual setup gives you more control but requires you to correctly configure all settings yourself.


Q: How do I know if I am connected via OAuth or API key?

A: Go to Back in stock alerts → Settings → Notifications and open the Klaviyo section. If you see a "Connected" status with a Disconnect button, you are using OAuth. If you see a field for entering a private API key, you are using the API key method.


Q: Can I use Catalog Lookup blocks alongside STOQ event variables?

A: It is not recommended. Catalog Lookup blocks rely on your Shopify catalog being synced to Klaviyo, and items that are out of stock may not be available for lookup — which is exactly when back in stock emails need to send. Use STOQ's event variables instead, as they are included directly in the event payload and do not depend on catalog sync.


Q: I switched from API key to OAuth. Do I need to update my flows?

A: Yes. The metric names change when you switch connection methods. OAuth uses metrics like "Back in stock alert (STOQ)" while API key uses "Stoq - Back In Stock Alert". Update your flow triggers to use the new metric names and re-verify the flow in STOQ.

Updated on: 06/05/2026

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