How to send automatic back in stock alerts with STOQ's Klaviyo app

STOQ's Klaviyo app lets you send automatic back-in-stock alerts through your Klaviyo account instead of STOQ's built-in email. When a product is restocked, STOQ triggers a Klaviyo event that fires a flow and emails your waiting customers - giving you full control over email design and delivery through Klaviyo's editor.

This guide walks you through switching to Klaviyo as your email provider, connecting the app, setting up flows for back-in-stock alerts and reminders, and verifying everything works.

Overview

STOQ can send back-in-stock notifications through three email platforms: STOQ (built-in), Klaviyo, or Shopify Flow. When you choose Klaviyo, STOQ stops sending emails itself and instead sends event data to Klaviyo, which triggers a flow to deliver the email.

Here is how it works at a high level:

1. A customer signs up for a back-in-stock notification through STOQ's Notify Me widget on your product page.
2. You restock the product in Shopify.
3. STOQ detects the inventory change and sends an event to Klaviyo with product and customer data.
4. Klaviyo receives the event, matches it to a flow, and sends the email using your Klaviyo template.

STOQ creates two metrics (event types) in your Klaviyo account for back-in-stock notifications:

Each metric triggers a separate Klaviyo flow with its own email template. This lets you customize the initial alert and the reminder email independently.

Prerequisites

Before you begin, make sure you have:

• An active Klaviyo account with a plan that supports flows
• Admin access to the STOQ app in your Shopify store
• A paid STOQ plan — Klaviyo as an email provider is not available on the free plan

Step 1: Switch to Klaviyo as Your Email Provider

To switch from STOQ's built-in email to Klaviyo for back-in-stock alerts:

1. From your Shopify admin, open the STOQ app.
2. Go to Back in stock alerts from the main menu.
3. Under the Notifications tab, click Customize email on the automatic notification step.
4. In the email customizer, find the Send emails through section.
5. Under Email platform, select Klaviyo.

Once selected, you will see Klaviyo-specific settings below the provider choice. The first step is to connect your Klaviyo account.

Step 2: Connect STOQ's Klaviyo App

STOQ connects to Klaviyo through an OAuth app — a secure connection that gives STOQ permission to create metrics, templates, and flows in your Klaviyo account.

How to connect

1. In the Klaviyo provider settings, under "1. Connect Klaviyo", click the Connect button.
2. A new tab opens with Klaviyo's authorization screen. Click Allow to grant STOQ access.
3. Return to the STOQ tab and refresh the page to confirm the connection.

Once connected, a green checkmark appears next to "Connect Klaviyo."

If you see a warning banner saying "Authorization was declined", it means you clicked Deny on the Klaviyo screen. Click Connect again and make sure to click Allow.

Step 3: Set Up Klaviyo Flows

After connecting, you need to set up the Klaviyo flows that will send your emails. STOQ offers two setup methods: automatic and manual.

Automatic setup (recommended)

Automatic setup lets STOQ create everything for you — metrics, email templates, and flows — with one click.

1. Under "2. Choose setup method", select Automatic setup.
2. Click Continue.
3. STOQ shows a progress banner as it works through the steps:

• • Creating templates
  • Creating flows
  • Activating flows

4. When finished, a success banner confirms the setup and lists the flows created:

• • Back in stock alert
  • Back in stock reminder

Both flows are now live in your Klaviyo account. You can view and customize them in Klaviyo under Flows.

Manual setup

If you prefer to configure flows yourself in Klaviyo:

1. Under the setup method, select Manual and click Continue.
2. STOQ displays the metric name for each notification (e.g., "Back in stock alert").
3. In your Klaviyo account, go to Flows > Create Flow > Create from scratch.
4. Set the flow trigger to the metric shown in STOQ. Under Your Metrics, find and select Back in stock alert (STOQ).
5. Add an Email action to the flow and design your template.
6. Set the flow to Live.
7. Back in STOQ, enter the exact flow name and click Verify to confirm the connection.

A green checkmark appears next to the metric name once verified.

Repeat this process for the Back in stock reminder 1 (STOQ) metric if you want to send reminder emails through Klaviyo as well.

Send test events

After setting up flows (automatic or manual), you can send test events to verify your setup:

1. In the Klaviyo provider settings, click Send test event.
2. This sends sample product data to Klaviyo so you can preview how events appear in your flow and template editor.
3. Check your Klaviyo account to confirm the event was received and the flow triggered.

Step 4: Verify Your Setup

After setup, verify that each flow is connected and active.

In STOQ

1. Go to Back in stock alerts > Notifications tab.
2. If Klaviyo is properly configured, the Customize email button for each notification step shows no warning banners.
3. Inside the email customizer, green checkmarks appear next to both "Connect Klaviyo" and the flow metric name.

In Klaviyo

1. Go to Flows in your Klaviyo account.
2. Look for the flows STOQ created (e.g., "Back in stock alert (STOQ)").
3. Confirm each flow status is set to Live (not Draft or Manual).

Customize Email Templates in Klaviyo

After setup, you can fully customize your back-in-stock email templates in Klaviyo's editor.

1. In Klaviyo, go to Flows and open the back-in-stock alert flow.
2. Click the email action to open the template editor.
3. Use Klaviyo's drag-and-drop editor to design the email with your brand colors, images, and layout.

STOQ sends rich event data — including product details, customer info, links, and shop information — that you can use as template variables in Klaviyo with the syntax {{ event.product_title }}.

Reset or Change Setup

If you need to start over or switch between automatic and manual setup:

1. Go to Back in stock alerts > Customize email > Send emails through.
2. Scroll to the bottom of the Klaviyo settings and click Reset setup.
3. This clears the flow verification and setup mode, letting you choose again.

To switch back to STOQ's built-in email, select STOQ under "Email platform" in the provider settings. Your Klaviyo flows will remain in your Klaviyo account but will no longer receive events from STOQ.

To disconnect the Klaviyo app entirely, go to Settings > Integrations and click Disconnect in the Klaviyo section.

Known Limitations

There are a few constraints to keep in mind when using Klaviyo for back-in-stock alerts.

• One email provider at a time. You cannot send back-in-stock alerts through both STOQ and Klaviyo simultaneously. Selecting Klaviyo disables STOQ's built-in email for those alerts.
• Klaviyo sending limits apply. Your emails are subject to Klaviyo's account limits and sending policies. High-volume restocks may encounter Klaviyo API rate limits.
• Paid STOQ plan required. Klaviyo as an email provider is only available on paid STOQ plans.
• Alerts still count toward your STOQ limit. Each back-in-stock event sent to Klaviyo counts as one notification toward your STOQ plan limit, regardless of which platform delivers the email.
• Slight delay possible. There may be a brief delay between a product coming back in stock in Shopify and the notification being triggered in Klaviyo.

Troubleshooting

Here are common issues and how to resolve them.

FAQs

Q: What is the difference between automatic and manual setup?

A: Automatic setup lets STOQ create the Klaviyo metrics, email templates, and flows for you in one click. Manual setup requires you to create the flow yourself in Klaviyo, set the trigger to the correct metric name, and verify it in STOQ. Automatic setup is recommended for most merchants.

Q: Do I need a paid Klaviyo plan to use this?

A: You need a Klaviyo plan that supports flows. Klaviyo's free plan includes flows for a limited number of contacts. Check your Klaviyo plan to confirm flows are available.

Q: Can I use Klaviyo for back-in-stock alerts and STOQ's built-in email for other notifications?

A: Yes. Email providers are configured per notification type. You can set Klaviyo for back-in-stock alerts and use STOQ's built-in email for preorder confirmations, or vice versa.

Q: What happens if my Klaviyo flow is paused or in draft?

A: STOQ will still send the event to Klaviyo, but the email will not be delivered. Make sure your flow status is set to Live in Klaviyo for emails to go out.

Q: How do I switch back to STOQ's built-in email system?

A: In the email customizer, change the email platform from "Klaviyo" back to "STOQ." Your emails will immediately be sent through STOQ's built-in system instead.

Q: Can I use my existing Klaviyo email templates?

A: Yes. If you use manual setup, you can create a flow in Klaviyo and use any existing template. Just make sure to add STOQ's event variables to display product and customer information correctly.

Q: Is the OAuth app connection required, or can I still use an API key?

A: The OAuth app is recommended for new integrations. If you previously set up a Klaviyo Private API key, it will continue to work. However, the OAuth app provides better security and enables automatic setup.

Q: Can I track email performance in Klaviyo?

A: Yes. All emails sent through Klaviyo flows appear in your Klaviyo analytics with standard metrics like open rates, click rates, and revenue attribution.

Updated on: 23/04/2026