Email Marketing Metrics That Matter: How the Top Email Agencies Drive Real ROI

If your email agency is still reporting open rates like it’s 2019, we have a problem.

The best DTC brands know that email marketing isn’t about blasting and hoping. It’s about performance. And performance needs to be measured with more than vanity metrics.

At Sticky Digital, we care less about opens and more about impact. Below are the email marketing metrics that actually matter—the ones that top agencies track, test against, and optimize for to drive real ROI.

1. Revenue per Recipient (RPR)

This is the holy grail. RPR tells you how much money your email made, per person who received it. It cuts through the noise of open and click rates and gets right to what matters: did it generate revenue?

A well-performing campaign flow should generate $0.10–$1.00+ per recipient, depending on audience, timing, and offer.

2. Click-to-Open Rate (CTOR)

Open rates have become murky post-iOS 15. But CTOR remains a powerful directional indicator. It shows you how many people who opened the email actually engaged with it.

We use CTOR to evaluate:

• Subject line + preview text alignment
• Email design clarity
• CTA placement and effectiveness

3. Flow Revenue Contribution

Flows should be doing the heavy lifting in your retention program. If 30–50% of your total email revenue isn’t coming from automated flows, something’s broken.

We track:

• Revenue per flow
• Flow completion rate
• Conversion by step (especially for post-purchase and winback)

Need a flow audit? Start here.

4. Campaign Revenue vs. Send Volume

More isn’t always better. One of the biggest mistakes brands make is sending just to hit a calendar, not a strategy.

We calculate:

• Campaign ROI by segment
• Revenue per 1,000 sends
• Lift from targeted vs. batch-and-blast sends

5. Deliverability Health

If your messages aren’t landing in inboxes, nothing else matters. We regularly monitor:

• Bounce rate
• Spam complaint rate
• Unsubscribe rate
• List growth vs. list decay

6. First-to-Second Purchase Rate

Email doesn’t just make money—it moves people through the funnel. One of our favorite KPIs? How many first-time buyers make a second purchase after going through a post-purchase email flow.

A small lift here means a huge LTV improvement.

7. Time Between Sends + Fatigue Rate

Too many emails and you burn your list. Too few and you leave money on the table. We optimize send cadence based on:

• Engagement by segment
• Drop-off and unsubscribe timing
• Performance of recent sends

What Great Email Agencies Do Differently

They don’t just send and report. They test, question, optimize, and tie every decision back to performance. If your current partner is leaning on open rate charts and vague “performance is solid” updates, you deserve better.

Want to see what strategic email reporting actually looks like? Let’s talk.

Final Thought

You don’t need more emails—you need smarter ones. And you need a partner who can prove why each message mattered.

At Sticky Digital, we build, test, and track every campaign and flow with a clear metric in mind: profitable growth. No fluff. Just performance you can see—and trust.

👉 Get in touch.