Cross-Sell and Upsell Emails: Logic, Timing + Klaviyo
How to run cross-sell and upsell emails for ecommerce: the difference, when to send, examples, and how product recommendation logic works in Klaviyo.
Table of contents
- Cross-sell vs upsell: what’s the difference?
- When to send cross-sell and upsell emails
- After delivery, not at checkout
- Not inside the order confirmation (if it’s transactional)
- At replenishment
- After a positive review
- Cross-sell and upsell email examples
- Supplements: the stack
- Skincare: the routine builder
- Apparel: complete the look
- Electronics: protect and extend
- Upsell to subscription
- Product recommendation logic in Klaviyo
- Level 1: Rules-based (you choose the pairing)
- Level 2: Product feeds and personalised recommendations
- Level 3: Predictive cross-sell timing (paid add-on)
- Level 4: Segment-aware recommendations
- Which level should you use?
- How to write cross-sell and upsell emails that convert
- Subject line ideas
- Metrics to track
- Common mistakes
- Engineer the second order
- Sources
A customer who has just bought from you is among the most likely people in your database to buy again. Cross-sell and upsell emails are how you turn that into a second order, and done well, they feel like help rather than selling.
This guide covers the difference between the two, when to send each, practical examples, and exactly how product recommendation logic works in Klaviyo (checked against Klaviyo’s help centre as of September 2026).
Cross-sell vs upsell: what’s the difference?
Cross-selling recommends a different product that complements what the customer bought. Upselling recommends a bigger, better or longer version of the same thing. A cross-sell grows the basket; an upsell grows the value of each purchase.
| Cross-sell | Upsell | |
|---|---|---|
| What you recommend | A complementary product | A larger, premium or longer-term version |
| Example | Bought a serum → recommend the SPF | Bought a 30-day tub → recommend the 90-day size or a subscription |
| Best timing | After first use, 1–3 weeks post-delivery | At reorder time, or before the first product runs out |
| Main metric | Items per customer, second-order rate | Average order value, subscription conversion |
| Main risk | Irrelevant recommendations | Pushing a bigger commitment before trust exists |
In ecommerce email, the two usually work together in the same post-purchase journey: cross-sell after first use, upsell at replenishment.
When to send cross-sell and upsell emails
After delivery, not at checkout
The customer needs to receive and like the first product before a recommendation lands. Typical windows:
- Fast-use products (apparel, accessories, food): 5–10 days after delivery.
- Routine products (skincare, haircare, supplements): 10–21 days, once they have built the habit.
- Considered purchases (electronics, furniture): 14–30 days, focused on accessories and care.
Not inside the order confirmation (if it’s transactional)
Many guides suggest recommendations in the order confirmation. If you send it from Klaviyo as a transactional message, Klaviyo’s rules prohibit products the person has not bought, coupons and marketing calls to action. Put the cross-sell in a separate marketing email in your post-purchase flow. Our order confirmation guide explains the rules.
At replenishment
The upsell moment for consumables is when the customer is about to reorder: a bigger size, a bundle, or a subscription. See our replenishment email flow.
After a positive review
A customer who has just left a five-star review is primed. Route them to a cross-sell or referral ask using the review event from your review platform.
Cross-sell and upsell email examples
These are structures to adapt, not scripts.
Supplements: the stack
- Trigger: first order of a magnesium product.
- Day 14 after delivery: “Getting the most from your magnesium”, covering routine and timing, then one complementary product for the same goal (for example a sleep-focused product for a sleep buyer), explained by outcome, not by claim.
- Replenishment time: upsell to a 90-day size or subscribe and save.
Skincare: the routine builder
- Trigger: bought a serum.
- Day 10: “Where your serum fits in your routine”, showing the step before and after, and recommending the missing step.
- Day 25: bundle upsell: the full routine at a set price.
Apparel: complete the look
- Trigger: bought trousers from a new collection.
- Day 7: “Three ways to wear them”, with pieces from the same collection that match.
Electronics: protect and extend
- Trigger: bought headphones.
- Day 14: case, cable or extended warranty. Accessories that protect the main purchase convert because they reduce risk.
Upsell to subscription
- Trigger: second one-off order of the same consumable.
- Email: “You’ve ordered this twice. Here’s how to never run out”, with the real subscription savings and flexibility.
Product recommendation logic in Klaviyo
This is where most cross-sell programmes are either engineered or left to chance. Klaviyo offers four levels of recommendation logic.
Level 1: Rules-based (you choose the pairing)
Build a flow on Placed Order (or Ordered Product for item-level logic), then use trigger splits by product, SKU or collection. Each branch gets a hand-picked recommendation in a static product block or image.
- Best for: smaller catalogues, and pairings you know work (serum → SPF, protein → shaker).
- Strength: complete control, and you can explain the pairing in the copy.
- Weakness: manual to maintain as the catalogue changes.
Level 2: Product feeds and personalised recommendations
Klaviyo product blocks pull from product feeds. Per Klaviyo’s help centre, the feed types are:
| Feed type | Personalised? | How it works |
|---|---|---|
| Best-selling products | No | Most sold, over the last 3 or 90 days, weighted to recent purchases |
| Most viewed products | No | Most viewed, over 3 or 90 days |
| Newest products | No | Recently added to the catalogue |
| Recently viewed | Yes | What the recipient viewed in the last 90 days |
| Added to cart | Yes | What the recipient added to cart in the last 90 days |
| Products a customer may also like | Yes | Collaborative filtering: predicts what they are likely to buy next from their past orders and similar customers |
Useful details:
- Feeds can be filtered by category (include or exclude), price range and stock level, so a supplement cross-sell can stay inside the supplements category.
- Klaviyo automatically excludes items without images, items the recipient already purchased, and out-of-stock items.
- New feeds typically take two days to a week to train.
- When there is not enough data for a personalised recommendation, the block falls back to the secondary recommender you choose (best-selling or most viewed).
- Views-based feeds need Viewed Product tracking; cart-based feeds need Added to Cart tracking.
Product feeds are available by default for Shopify, WooCommerce, BigCommerce, Magento and several other ecommerce integrations.
- Best for: larger catalogues where manual mapping does not scale.
- Tip: combine levels. Use a trigger split for the main pairing, then a personalised feed block constrained to the same category underneath.
Level 3: Predictive cross-sell timing (paid add-on)
Klaviyo’s product analysis reporting can drive a dynamic cross-sell flow triggered by a Best cross-sell date property, with a Next best product block for the recommendation. Klaviyo offers a prebuilt “Next best product cross-sell” flow. Klaviyo states that the Advanced KDP and Marketing Analytics features behind this are not included in the standard marketing application and require a subscription.
- Best for: brands with enough order volume for the model to be meaningful, who want timing and product chosen per customer.
Level 4: Segment-aware recommendations
Klaviyo also documents personalising recommendations by RFM group, so champions, at-risk customers and new buyers see different recommendations. This pairs well with Klaviyo segmentation you already run.
Which level should you use?
| Catalogue | Order history | Start with |
|---|---|---|
| Under ~30 products | Any | Level 1, rules-based |
| 30–300 products | Moderate | Level 1 for hero products + Level 2 feeds |
| Large catalogue | Strong | Level 2, then test Level 3 |
How to write cross-sell and upsell emails that convert
- Lead with their product, not yours. “How to get the most from your serum” earns the right to recommend.
- Explain the pairing. One sentence on why these go together beats a grid of six products.
- One to three recommendations. More choice, fewer clicks.
- Show the real value. For bundles and subscriptions, show the saving plainly.
- Respect margin. If the add-on is low-margin, do not discount it further.
- Tie to thresholds. “Add the SPF and your next order ships free” works if your free shipping threshold sits just above the original order value.
- Keep supplement copy compliant. Recommend by goal and routine, not by health claim.
Subject line ideas
- The perfect partner for your {{ product }}
- Getting more from your {{ product }}
- What {{ product }} customers add next
- Complete your routine
- Never run out: save with a subscription
Metrics to track
- Second-order rate within 60 or 90 days for customers who enter the flow.
- Placed-order rate and revenue per recipient per email.
- Items per order and AOV on orders attributed to the flow.
- Recommendation click-through by block type (rules-based vs feed), to see which logic works.
- Unsubscribe rate: a rise suggests recommendations are too early or too generic.
Common mistakes
- Recommending what they already own. Feeds handle this; static blocks do not.
- Sending before delivery.
- The same best-seller for everyone.
- Too many products in one email.
- Promotions inside transactional emails.
- Upselling a subscription on the first email after the first order. Earn trust first.
Engineer the second order
Cross-sell and upsell emails are where the jump from one order to two, and from two to many, is built. The logic behind the recommendation matters more than the design around it. They sit alongside replenishment and review requests in the post-purchase part of your drip campaign set.
If you want recommendation logic mapped to your catalogue and built into your flows, our flow automation team does that, or start with a free Klaviyo audit to see how much second-order revenue your account is leaving behind.
Sources
/ Frequently Asked Questions
Q.01 What is the difference between cross-selling and upselling? +
/ Answer
Cross-selling recommends a different, complementary product to go with something the customer bought or is considering, such as a case with a phone or a cleanser with a moisturiser. Upselling recommends a bigger, better or longer version of the same thing, such as a larger size, a premium formula, a bundle or a subscription. Cross-sells grow the basket; upsells grow the value of each item.
Q.02 What is a cross-selling email example? +
/ Answer
A skincare customer who bought a vitamin C serum receives an email ten days after delivery explaining how to layer it, then recommending the SPF that protects the results, with a link to add it to their next order. The recommendation is tied to what they bought, explained in terms of their outcome, and timed for when they have started using the first product.
Q.03 When should you send a cross-sell email? +
/ Answer
After the customer has received and started using their first product, usually 7 to 21 days after delivery depending on the category, and never inside the order confirmation if it is sent as a transactional email. Earlier cross-sells can work in the post-purchase thank-you for obvious add-ons, but a recommendation lands best once the customer has had a good experience.
Q.04 Is cross-selling good or bad for customers? +
/ Answer
It is good when the recommendation genuinely helps the customer get more from what they bought, and bad when it is a random best-seller pushed at everyone. Relevance is the dividing line. A cross-sell based on what the customer bought, explained in terms of their result, feels like service. A generic 'you might also like' grid feels like an advert and trains people to ignore you.
Q.05 What are common cross-selling mistakes? +
/ Answer
Recommending products the customer already owns, sending cross-sells before the first order has arrived, showing too many options, ignoring margin so the add-on is discounted below profit, and recommending best-sellers with no connection to the original purchase. Another common mistake is mixing promotional cross-sells into transactional emails, which breaks platform rules such as Klaviyo's and blurs the legal line.
Q.06 How does Klaviyo recommend products in emails? +
/ Answer
Klaviyo product blocks pull from product feeds. Classic feeds show best-selling, most viewed or newest products. Personalised feeds show items a customer recently viewed or added to cart, or 'products a customer may also like', which uses collaborative filtering on past orders and similar customers. Feeds can be filtered by category, price and stock, and exclude items the recipient already bought.
Shows our articles higher in your Google results. Takes one click.