When a product comes back in stock, the first people to notify are the customers who specifically asked to hear about it. For Shopify stores, that normally means setting up a back-in-stock app that lets shoppers subscribe to an unavailable product and automatically notifies them when the relevant item is available again.
That takes care of the obvious audience, but it is not the only opportunity. A customer may have added the product to cart before it sold out, visited the product page several times, or recently spent time browsing similar products. Depending on how strong those signals are, the restock may also justify a broader email campaign.
The first step is to get the basic notification setup right. After that, you can decide how far beyond the waitlist it makes sense to go.
How to set up back-in-stock emails in Shopify
Shopify can track inventory and detect when a product variant moves back into stock, but it does not send the restock email for you. To add a Notify me when available option to your storefront, collect customers who are waiting for a particular item, and send them an email when it returns, you will need a back-in-stock app from the Shopify App Store.
Choose an app that can add the notification form to sold-out product pages, record the product or variant each customer is waiting for, maintain that waitlist, and trigger an email when inventory returns. Some of these apps also connect with Shopify Flow, which gives you more control over what happens after an inventory change. Shopify lists supported back-in-stock apps among its Flow app connectors.
Once the app is installed, customers see an option such as Notify me when available when the item they want is sold out. When they enter their email, the app records their interest in that item.
Where products have multiple variants, the subscription should be attached to the specific variant. If a shopper is waiting for a black size M, the notification should not go out simply because another size or color has returned.
Shopify also needs to be tracking inventory for those products. Shopify Flow has a native Product variant back in stock trigger that starts a workflow when the inventory for a variant increases from 0 or less to 1 or more, and it requires the product to have Inventory tracked switched on. The change itself can come from an order, a manual inventory edit, or an app.
You do not need Shopify Flow for this. Many back-in-stock apps already handle the full process from subscription to notification. Flow is more useful when you want to add your own conditions or connect the inventory event to other systems and actions.
The notification email itself can stay straightforward. The customer already knows the product and has asked to hear when it returns, so the email mainly needs to confirm that it is available, show the relevant product or variant, and give them a direct route back to the product page. If inventory is limited, that can be mentioned, but there is no reason to add artificial urgency.
For the wider question of which inventory movements are worth an email at all, how to use Shopify inventory data to come up with campaigns and browse abandonment vs cart abandonment are the two to read next.
Nexie is an AI-native ESP for e-commerce brands. It reads your customer data across engagement, recency, category interest and lifetime value together, surfaces the audiences worth campaigning to, and builds those campaigns for your team to review and approve, inside the guardrails and marketing policies you set. See how it works →