The single biggest mistake people make with a back-in-stock Klaviyo flow is treating it as a simple transactional alert instead of a high-intent conversion campaign. You have a customer who explicitly raised their hand to say, “I want to give you money for this specific thing.” Sending them a generic, uninspired notification is a huge waste of that buying signal.
So many brands fall into the trap of using the default, one-size-fits-all template. It’s easy to just switch it on and forget it, but it’s lazy. This approach fails to acknowledge the customer’s specific interest and misses a chance to rebuild the excitement they felt when they first wanted the product. This costs you conversions because the email feels impersonal and functional, not desirable. One episode of Shopify1Percent makes a great case for building advanced flows with specific conditions. The fix is simple: use Klaviyo’s dynamic blocks to pull in the exact product title, image, and description. The email should look like it was written just for that product, because that’s the only one the customer cares about.
Another common error is sending a single notification and then giving up. The thinking is that if they were truly interested, one email is enough and more would be annoying. But inboxes are a war for attention. Your one email will get missed. People get busy, they see it on their phone and forget to act, or it just gets buried. Every lost sale from that list is a failure to convert a nearly guaranteed customer. The fix is to think in sequences. Create a short, 2-to-3 email flow. The first is instant: “It’s back!” The second, sent a day later, can add urgency like “Our restock is selling fast” or build confidence by including top reviews for that specific product.
Perhaps the most costly mistake is how the waitlist itself is perceived. Brands chase new, cold leads while sitting on a valuable segment of customers who have told them exactly what they want to buy. Nik Sharma made the point on Limited Supply that for high-intent customers, “You’re not creating demand. You’re just catching it.” People on your back-in-stock list are the definition of high-intent. The fix is to treat them like the VIPs they are. Don't just send them an email; make the restock an event for them. Give them an hour of early access before the product goes live for everyone else. This small gesture respects their patience and dramatically increases the odds that you will catch that intent.
A great back-in-stock flow feels less like an alert and more like a personal shopping service.
