Automated messages triggered by what a customer just did. They’re a small share of sends and a large share of revenue, because they arrive when someone is paying attention.
A campaign is a message you decide to send to a group on a date. A flow is a message a customer triggers by doing something: signing up, leaving a cart, receiving an order, going quiet. Flows arrive at the moment of highest attention, which is why they earn so much per message.
Klaviyo’s 2026 benchmark report, across more than 183,000 of its customers, found that flows produced about 41% of email revenue from just 5.3% of sends, and earned roughly 18 times the revenue per recipient of campaigns Reported. Their order rate was 2.11% against 0.16% for campaigns. Omnisend reported a similar pattern in its 2025 data: automations were 2% of sends and 30% of email revenue Reported. Both are vendors with a stake in email, and both averages include a lot of neglected accounts. The direction is the point.
Flows are the floor. Campaigns are the ceiling. Build the floor first.
| Flow | Triggered by | Its job | First thing to get right |
|---|---|---|---|
| 1. Welcome | A new subscriber | Turn a sign-up into a first order, and teach what the brand is | That it’s live. Then deliver the promised offer in the first message, immediately. |
| 2. Cart and checkout abandonment | A started checkout or a cart with an email attached | Recover orders that were nearly placed | Timing. Test the first message at about an hour against later. |
| 3. Post-purchase | A first order | Make the first experience good and set up the second order | Branch on the first product. A skincare buyer and a gift buyer need different next steps. |
| 4. Browse abandonment | A known subscriber viewing products without adding to cart | A gentle reminder, often with reviews or a comparison | Suppress people who just got a cart email. |
| 5. Winback | A customer passing their usual reorder window without buying | Bring lapsed customers back before they’re gone | Time it from your reorder curve, not a round number. |
| 6. Sunset | A subscriber with no engagement for a long stretch | Last chance to re-engage, then suppress | That it exists. It protects deliverability for everyone else. |
Once those six are healthy, add the ones your category earns: replenishment reminders for consumables, a VIP series for your top customers, back-in-stock, price drop, birthday, review requests and cross-sell.
It’s the flow most worth getting right, because every subscriber passes through it exactly once. The first message goes immediately and delivers whatever the sign-up promised, with no preamble. The next few, over the following week or two, do the work of a good salesperson: say what the brand is and isn’t, show the product that most first-time buyers choose, answer the most common objection from your reviews, and show proof from customers like the reader. Exit anyone who buys into the post-purchase flow straight away. If the sign-up offer has an expiry, say so once, near the end, and mean it.
From my work: the flows most accounts have are fine on paper and broken in the wiring. When I audit an account, these are the faults I find most often.
Group flows in your platform by the stage of the customer’s life they serve: getting a first order, recovering an order, after the order, and bringing someone back. When they’re organized that way, gaps are obvious.
Revenue per recipient: revenue attributed to the flow divided by the people who entered it. It lets you compare a welcome series with a winback flow fairly, and it shows when a change helped. For the flows that matter most, add a holdout, a random slice of people who enter the flow and receive nothing, so you know what the flow adds beyond orders that would have happened anyway. The Second Order covers holdouts on flows in detail.
This is one chapter of The Whole Machine, which is free and readable in full on a single page with no form in front of it.