When a product goes out of stock, most stores lose that sale permanently. The shopper wanted the product. They found it. The stock was gone. Without a structured way to capture and re-engage that demand, the revenue disappears.

Swym Back in Stock Alerts captures the demand signal when a shopper subscribes for a restock notification. Shopify Flow automates the re-engagement when inventory returns. Together, they close the gap between stockout and sale.

Back-in-stock emails benchmarked across Swym merchants average a 30 to 35% click-through rate and around 20% conversion. This workflow runs entirely on autopilot.

Who This Playbook Is For

Marketing teams running re-engagement campaigns and operations or inventory teams managing out-of-stock recovery. Both functions benefit from this workflow: marketing gets automated sends, operations gets demand data during the stockout.

What You Will Build

When a shopper subscribes for a back-in-stock notification and the product returns to inventory, Shopify Flow fires automatically. The shopper receives a personalised alert via email or SMS. No manual send, no list export, no delay.

Click Select Trigger. In the Swym section, select Subscribed for Back-in-Stock Alert. This fires when a shopper submits their email on the out-of-stock alert widget on your product page.

Metadata passed: shopper email, product ID, product title, variant, and product URL.

Common conditions to focus the workflow:

• Product price above a threshold (prioritise high-AOV recovery first)
• Customer segment: existing customers vs. new subscribers
• Product category: focus on specific lines first when testing

When the shopper subscribes, you may want to send an immediate confirmation: we have your alert, we will let you know when it is back. This is optional but reduces shopper uncertainty.

Add a customer tag: back-in-stock-subscriber. This allows you to build a segment in your CRM for this audience.

Create a second workflow with the trigger: Product back in stock (Shopify native trigger). Add a condition: Customer tag contains back-in-stock-subscriber.

Set the action: add the customer to a Klaviyo flow or send an HTTP request to your SMS platform. Your message fires automatically when the product returns.

The two workflows work together: the first captures the subscriber, the second re-engages them when stock returns.

What to Include in the Back-in-Stock Message

Subject / first line: name the product directly. 'Your [Product Name] is back.'

Body: product image, current price, stock status ('Limited stock available' increases urgency without fabricating scarcity).

CTA: single button. 'Add to cart now.'

Optional: if stock is limited, add a low-stock line pulled dynamically from Shopify inventory data.

What Success Looks Like

1. Subscribers captured per product per stockout period
2. Re-engagement send rate when product restocks
3. CTR on back-in-stock message (benchmark: 30 to 35%)
4. Conversion rate from back-in-stock click (benchmark: around 20%)
5. Revenue recovered: orders placed within 7 days of receiving the alert