Why email attribution is understated
Email clicks generate last-click attribution in most analytics setups. A customer who receives an email, does not click, sees a Meta retargeting ad three days later, and then searches the brand name on Google to purchase is attributed to Google organic or branded search. The email that kept the brand top of mind during those three days gets no credit.
Post-purchase surveys consistently show that 20 to 35 percent of customers who converted through other last-touch channels received an email from the brand in the prior seven days that they read or opened but did not click. Email influenced the purchase but the click path went elsewhere.
The revenue metrics that matter in email
Open rate and click rate are engagement metrics, not revenue metrics. The metrics that determine email's actual business contribution are revenue per recipient, list growth rate, and list decay rate. Revenue per recipient tells you how much money each email generates per person on your list. That number, multiplied by your list size, gives you your email channel revenue potential.
List decay is the metric most brands ignore. Email lists shrink through unsubscribes, spam complaints, and bounces at a rate of 20 to 30 percent per year for typical DTC brands. If your list is not growing faster than it is decaying, your email channel revenue is compounding negatively.
The flows versus campaigns distinction
Email performance comes from two types of sends: automated flows (welcome series, abandoned cart, post-purchase, win-back) and manual campaigns (newsletters, promotions, product launches). Flows are higher-converting because they are triggered by specific customer behavior and arrive at contextually relevant moments. A post-purchase email arrives when the customer is already engaged. A win-back email arrives when the customer's attention needs to be recaptured.
Campaigns reach your entire list at once, which means they reach subscribers at every stage of engagement simultaneously. Segmenting campaigns by engagement tier, high-engagement subscribers receiving one version and low-engagement subscribers receiving a re-engagement variant, consistently improves campaign performance by 20 to 40 percent compared to broadcast sends.
Measuring email contribution margin
Email has extremely high contribution margins compared to paid media. The fixed costs are ESP fees and content creation. The variable cost per send is near zero. A list of 20,000 subscribers generating 4 euros revenue per send costs roughly 200 euros to manage per month and generates 80,000 euros in monthly email revenue at typical DTC email volume.
The mistake is treating email as a free channel and not accounting for the opportunity cost of subscriber attention. Sending promotional emails too frequently degrades list quality, increases unsubscribe rates, and reduces per-send revenue over time. Track unsubscribe rate per campaign type and revenue per recipient per month. If revenue per recipient is declining month over month, you are degrading your list faster than you are monetizing it.
List building as a capital allocation decision
Growing an email list requires acquisition spending: paid social lead generation, pop-ups, in-person events, referral programs. Treat list building as capital allocation. Every subscriber you acquire has a projected lifetime email revenue based on your revenue per recipient and average subscriber lifespan. If a subscriber generates 12 euros per year in email revenue on average and stays on your list for two years, their email LTV is 24 euros. You should be willing to spend up to 8 euros to acquire that subscriber, which is a 3:1 return.
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