- Short answer
- Flow can react when a variant restocks, but a "Notify me" sign-up and the restock email need an app or a tool like Klaviyo.
- Flow trigger
- Fires when a variant goes from 0 or less to 1 or more; needs Inventory tracked on
- Flow email
- Send internal email can't take its address from a variable, so Shopify points it at staff
- Shopify Messaging
- 11 ready-made automation types as of October 21, 2026; none is back in stock
Can Shopify Flow email shoppers when stock returns?
Flow's Product variant back in stock trigger starts a workflow when a variant's inventory goes from 0 or less to 1 or more, only for products with Inventory tracked on (the Track quantity setting in the Inventory section of the product or variant).
The trigger hands the workflow the variant and nothing about who asked for it. Flow's Send internal email can't take its address from a variable, so Shopify says it is best used for emails to staff.
This trigger allows actions that affect products and variants, such as bringing a hidden variant back: Shopify usually pairs it with Publish product variant, the setup in our sold-out variants answer.
Does Shopify Messaging have a back-in-stock automation?
Not among its ready-made ones: as of October 21, 2026, Shopify Messaging offers 11 automation types, none for restocks. For a custom one, Shopify points you to Flow, whose own back-in-stock trigger has the gap above: no record of who asked.
Our check that day for a built-in restock sign-up covered the Flow, Messaging, notifications and inventory help; customer notifications there cover orders, shipping and account activity.
Who collects the “Notify me” sign-ups: an app or Klaviyo?
Shopify's App Store lists back-in-stock apps under Stock alert apps. Listings we read on October 21, 2026 include Amp Back in Stock & Preorder +, Crawlapps' Back in Stock Alert & Preorder and SetuBridge's Back In Stock Alert‑ Notify Me, each with a free plan or free install. Or use Klaviyo's back in stock form with a back in stock flow:
- Notify me button on out-of-stock products, variants and collection pages (SetuBridge)
- Email, SMS and push (Amp); email, SMS or WhatsApp (Crawlapps)
- Notify me button on any out-of-stock product page once published
- A back in stock flow you build sends the email; by default, to all subscribers at once
- SMS alerts need explicit consent to promotional texts
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