Back-in-Stock Postcards: Bring Customers Back When the Product Returns
Stock-outs are frustrating for customers — but they're also a retention opportunity. When a customer adds an item to their wishlist or signs up for back-in-stock notification, they're demonstrating strong purchase intent. The standard back-in-stock email achieves 20–25% open rates and 3–5% conversion. A physical postcard sent when the item returns captures customers who missed the email and converts at a meaningfully higher rate due to the physical reminder's persistence.
Why back-in-stock postcards work
A customer who wishlisted or requested back-in-stock notification has already made a near-purchase decision. The only barrier was availability. When the item returns, their intent is still high — but only if they're reminded promptly. Email back-in-stock alerts have a 48-hour window of peak effectiveness. After 48 hours, purchase intent drops significantly. A postcard arriving 3–5 days after the restock catches customers who missed the email alert, in the second peak of intent.
Technical setup
Back-in-stock postcards require integration with your inventory management system or e-commerce platform's back-in-stock notification data. For Shopify stores, apps like Back In Stock by Swim notify customers when inventory is replenished and can tag customers or create segments that Mayday reads. For WooCommerce, similar plugins exist. The trigger in Mayday fires when a customer is tagged as "back-in-stock notified" and uses the product information to personalise the postcard.
What to include on a back-in-stock postcard
The notification must be timely and specific: the product name, an image, the fact that it's back in stock, and a direct QR code to the product page. Include a limited-time offer or urgency message ("Only 50 remaining") to leverage the existing purchase intent. A personalised promo code for a small discount (5–10%) can tip hesitant customers who are comparing options. The tone should be service-oriented, not sales-heavy — you're doing the customer a favour by telling them.
Prioritising high-value back-in-stock customers
Not every back-in-stock customer warrants the cost of a postcard. Filter by: customers who wishlisted a product worth €40+, customers with a purchase history (indicating genuine purchase intent), and customers who didn't open the back-in-stock email. This focus on high-intent customers reduces volume while maintaining ROI. A batch of 100 targeted postcards at €199 total, converting at 10%, generates 10 purchases at an average €65 value — €650 revenue against €199 spend.
Scarcity-driven campaigns
For limited-edition restocks or small production runs, a postcard becomes an exclusive notification. "We restocked 100 units of [product] — here's early access" is a compelling message that combines back-in-stock notification with scarcity marketing. Send these postcards only to your highest-LTV customers who previously expressed interest. The combination of exclusivity and genuine scarcity drives some of the highest conversion rates across all direct mail campaign types.
Notify customers when their wishlisted items are back with a postcard they can't miss.
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