Open rate is the easiest email metric to report and, on its own, one of the least useful ones to manage against. Apple's Mail Privacy Protection alone inflates open rates for a huge share of any list, which means a dashboard full of green open-rate numbers can sit right on top of a flat revenue line.
Here's what we actually watch on every client account.
The metrics that map to revenue
- Click-to-open rate (CTOR). This tells you whether the content and offer inside the email are working — independent of subject-line noise or inflated opens.
- Revenue per recipient (RPR). Not revenue per campaign, not total revenue — revenue divided by every person who received the send. This is the number that lets you compare a 5,000-person list against a 50,000-person list honestly.
- List health, not list size. A 20,000-person list with 40% engagement outperforms a 100,000-person list with 8% engagement, every time, on both revenue and deliverability.
- Flow-driven revenue vs. campaign-driven revenue. Welcome series, abandoned cart, post-purchase, and win-back flows should be doing a disproportionate share of the work relative to the one-off campaigns — if they're not, the automation layer needs attention before the campaign calendar does.
Why deliverability is a growth metric, not an IT problem
A list with poor engagement doesn't just convert worse — it actively damages sender reputation, which lowers inbox placement for every future send, including the ones your best customers actually want to see. Suppressing unengaged subscribers isn't a loss; it's protecting the asset.
Segmentation beats volume
The highest-performing accounts we run aren't sending more email — they're sending more relevant email to smaller, better-defined segments. Purchase history, engagement recency, and stated preferences do more for revenue per send than any subject-line trick.
The takeaway
If your email reporting stops at open rate and total revenue, you're missing the two numbers — CTOR and revenue per recipient — that actually tell you whether the program is getting better or just getting bigger.