Most ecommerce brands focus on acquiring new customers and recovering abandoned carts. These are important, but they overlook one of the most profitable email flows: cross-selling to existing customers. A customer who has just purchased from you is in the best possible state to buy again — they trust your brand, they are engaged, and they have a product that may benefit from complementary items.
This guide covers how to build effective cross-sell flows in Klaviyo that increase customer lifetime value without being pushy. We implement these flows for every brand we work with through our Klaviyo email marketing services.
What is a cross-sell flow?
A cross-sell flow is an automated email sequence triggered after a customer purchases a product, recommending complementary products they are likely to want. The flow targets the post-purchase window when the customer is engaged with your brand and receptive to additional recommendations.
Why cross-sell flows work
- Timing — The customer just bought from you and has your brand top of mind
- Trust — They have already demonstrated trust by completing a purchase
- Relevance — Recommendations are based on what they actually bought, not guesses
- Lower CAC — Selling to existing customers costs far less than acquiring new ones
A well-built cross-sell flow typically generates 5 to 15 per cent of total email revenue for ecommerce brands. That is revenue from customers who would not have made a second purchase without the prompt.
When to send cross-sell emails
Timing is critical for cross-sell emails. Send too early and the customer has not received their product yet. Send too late and the purchase excitement has faded.
Recommended timing
| Timing | Purpose | |
|---|---|---|
| Cross-sell email 1 | 3–7 days after delivery | Primary product recommendation |
| Cross-sell email 2 | 10–14 days after delivery | Broader recommendations or content |
Delivery-based timing
Ideally, trigger cross-sell emails based on the Shopify Fulfilled Order event rather than the Placed Order event. This ensures the customer has received their product before you recommend more. If delivery tracking is not available, use a conservative delay of 10 to 14 days after purchase.
Product mapping strategy
The most important element of a cross-sell flow is recommending the right products. Random recommendations feel spammy. Relevant recommendations feel helpful.
Manual product mapping
For stores with a focused product catalogue, manually define which products complement each other. Create a mapping document:
| Purchased product | Cross-sell product 1 | Cross-sell product 2 |
|---|---|---|
| Running shoes | Running socks | Shoe cleaning kit |
| Face moisturiser | Eye cream | SPF serum |
| Coffee beans | Grinder | Filter papers |
Algorithmic recommendations
For stores with large catalogues, use Klaviyo's product recommendation engine. It analyses purchase patterns across your customer base to identify which products are frequently bought together. The "customers who bought X also bought Y" approach works well at scale.
For more on personalisation, see our ecommerce personalisation guide.
Setting up the flow in Klaviyo
Trigger
Use the Placed Order metric as the trigger. If you have delivery data, you can use Fulfilled Order instead for better timing.
Flow filters
- Has not placed another order since starting this flow (they may have already cross-sold themselves)
- Has not been in this flow in the last 30 days (prevents over-messaging repeat buyers)
Conditional splits
Add conditional splits based on the purchased product category. This allows you to show different cross-sell recommendations depending on what the customer bought. Use the order event's product properties to route customers to the appropriate email content.
Dynamic product recommendations
Klaviyo's dynamic product recommendation blocks can automatically populate cross-sell emails with relevant products. Configure the recommendation algorithm to show products frequently purchased with the customer's recent order, products from complementary categories, and products the customer has viewed but not purchased.
Email content and design
Cross-sell email 1: The complementary recommendation
Subject line: Complete your [product category] setup. Content: acknowledge the recent purchase, explain why the recommended products complement it, show two to three product recommendations with images and prices, include a clear CTA to shop. Tone: helpful, not pushy.
Cross-sell email 2: The broader recommendation
Subject line: More you might love. Content: a wider selection of product recommendations based on the customer's browsing and purchase history, customer reviews and social proof, and a bundle offer if applicable. This email casts a wider net for customers who did not respond to the targeted first email.
Measuring cross-sell performance
Track these metrics to evaluate your cross-sell flow:
- Second purchase rate — What percentage of first-time buyers make a second purchase within 30 days?
- Revenue per recipient — How much revenue does the cross-sell flow generate per person who enters it?
- Click-through rate — Are customers engaging with the product recommendations?
- Average order value of cross-sell purchases vs average order value overall
Advanced cross-sell techniques
Bundle offers
Create product bundles that include the purchased product plus complementary items at a small discount. Promote these bundles in your cross-sell flow for higher AOV.
Subscription conversion
For consumable products, use the cross-sell flow to promote a subscription. If someone bought a one-time supply of coffee, the cross-sell email can offer a subscription at a discount.
Category-specific flows
Build separate cross-sell flows for your top product categories, each with tailored messaging and recommendations. This provides a better customer experience than a generic cross-sell flow. For more on essential flows, see our 7 Klaviyo flows guide.
Cross-sell flows are one of the most underused revenue opportunities in ecommerce email marketing. They target your best audience (recent buyers), with the best timing (post-purchase excitement), and the most relevant content (complementary products). The setup takes a few hours; the revenue compounds indefinitely.
If you want help building cross-sell flows or optimising your post-purchase email strategy, get in touch. We build these flows as part of our Klaviyo email marketing services.
