Your one-time buyers are already paid for. Count who you can reach, then work them in phases.
Your one-time buyers already cost you one acquisition each. That money is spent whether you mail them or not. A second order from them costs only the program that earns it. Before you forecast anything, count how many of them you can still reach. Then work them in phases, with a group held back from the first send to prove what the program did.
Base: the one-time buyers you can lawfully and safely mail: consented, not suppressed, not bounced, and recent enough to be deliverable. Count them before you price them.
The number shrinks at every cut. A forecast built on the raw total prices people you can't mail, so the program misses its number before the first send. The reachable count goes at the top of the plan, and every rate you forecast is a rate of that count. It takes an afternoon if suppressions live in one platform, a few days if they're spread across several.
Keep two populations apart. A winback aimed at customers who cancelled a subscription usually recovers a low single-digit share of them. One-time buyers who never cancelled anything are a different group. They went quiet for different reasons. In both cases, the rate you plan on is an assumption until a holdout confirms it.
In the skincare file, 13,526 customers bought once. That is the starting count, before any of the cuts above. Forecast assumption: 10% come back for a second order. The full scenario table, with what each rate costs to reach, sits in The Budget Ask.
Old files make the count harder and more important. From 2019 to 2021 I ran growth and retention across a portfolio of acquired heritage retail brands, including Pier 1 Imports and RadioShack, whose customer files had been dormant for years. The lesson holds on any back file. Dormant doesn't mean dead, and a dashboard can't tell you which records are which.
Sort by age first and product second. A buyer from the last two years who has clicked anything since is still a customer. A buyer with an old order and no activity since is a deliverability risk. Mail both in one send and inbox placement drops for the whole file. So re-permission the oldest tiers in small waves, and only the ones who respond ever see an offer.
A customer file you inherit with a brand doesn't come with fresh permission. Carry over every unsubscribe. Find out what the old privacy policy promised and what the sale terms allow. Ask your email platform before the first send, including a re-permission send. And treat the SMS list as un-consented until customers opt in with you. Have counsel sign off before any of it goes out.
Each phase narrows the audience and raises the cost per contact, so each one has to earn the next. Write the stop condition before the phase starts. A program with no written line to cross never gets stopped. Read every phase against the same holdout so the phases stay comparable.
Add SMS only for customers who gave you written consent to text and haven't replied STOP. If the list has been quiet a year or more, run it through the FCC's Reassigned Numbers Database first. Send between 8am and 8pm in the customer's time zone, which sits inside both the federal and the Florida windows.
Run the paid layer only if the matched audience clears the ad platform's minimum audience size. Customer lists match well below 100%, so a small segment can fall under the minimum after matching. If it doesn't clear, Phase 2 is a second email sequence. Only upload customers your privacy policy lets you share with ad platforms, and leave out anyone who opted out of sale, sharing or targeted ads.
Phase 3, your top tenth, runs on status rather than offers, as Your Top Ten Percent lays out.
Hold out 10% of the reachable base before Phase 1 sends. Keep them out of every phase, paid included, until the program ends. The rate you report is the treated group's second-order rate minus the holdout's.
The holdout is larger than a standing program needs. You pass through a finite base once, and there is no second run to read. Cohort is how this program gets run and defended, so the held-out group has to be big enough to read by cohort. Read it at day 90 and again at day 180, because most of the value a customer adds after day 30 arrives after day 90.
This is one chapter of The Second Order, which is free and readable in full on a single page with no form in front of it.