Email marketing has had a bit of a glow-up over the years. What used to be a numbers game of blasting to a giant list, watching open rates soar, and celebrating a 2% click-through is now a strategic art form. The rules have changed. The audience has changed. And, surprise: the metrics that matter have changed, too.

So why are so many marketers still acting like it’s 2010?

If you’re still gauging your email success by opens alone, we need to have a little heart-to-heart. Because in 2025, the inbox is sacred territory, and winning it requires more than just attention. It demands trust, timing, and a tighter focus on the metrics that tell the real story. Let’s talk about what actually matters now and why chasing vanity stats might be holding you back.

First, Let’s Talk About the Great “Open Rate” Lie

We’ll keep this one short and painful. Open rates used to be the holy grail of email metrics.

“Look! 40% of people opened our message! We’re crushing it!”

But between Apple Mail Privacy Protection (hello, pixel blocking), Gmail’s auto-categorization, and the rise of mobile-first readers, open rate accuracy has taken a nosedive. Apple’s update alone inflated opens by as much as 30–50%, according to HubSpot and Litmus studies.

In other words, that impressive open rate may be a ghost metric.

Does this mean you should ignore open rates altogether? Not quite. You can still track relative trends—like whether subject lines are improving or a specific segment is responding better—but open rate alone is no longer the guiding star. It's just the appetizer.

Deliverability: The Metric Most Marketers Ignore (Until It’s Too Late)

Deliverability is the unsung hero of email performance. If you’re seeing consistently low engagement, or if you’ve noticed your click rates plummet even though “everything looks fine,” your emails might not be reaching your audience at all. And it’s not just spam filters causing problems. It’s sender reputation, list hygiene, frequency, authentication protocols (SPF/DKIM/DMARC), and yes, even your email content.

What to watch:

Bounce Rate: Anything Over 2% Is a Red Flag

A high bounce rate doesn’t just mean a few undelivered emails—it tells inbox providers that your list might be outdated, sketchy, or poorly maintained. Hard bounces (fake or invalid addresses) are especially damaging. Even a bounce rate over 2% can hurt your sender reputation, triggering spam filters and tanking deliverability. The fix? Clean your list regularly and use verification tools like NeverBounce or Kickbox before sending big campaigns.

Spam Complaint Rate: 0.1% Is the Danger Zone

Spam complaints are arguably the fastest way to burn your sender reputation. When even a tiny fraction of recipients hit that “this is spam” button—more than 0.1%—Gmail, Yahoo, and friends take notice. And not in a good way. It tells them your emails are unwelcome, irrelevant, or worse, deceptive. To stay in the safe zone, make sure your opt-ins are clear, your content is expected, and your unsubscribe link is easy to find (and painless to use).

Inbox Placement Rate (IPR): Know It Before You Hit “Send”

Most marketers assume “delivered” means “in the inbox,” but that’s not always true. Your email might be marked as delivered even if it lands in the spam folder or Promotions tab. Inbox placement rate shows you the real visibility of your message. Tools like GlockApps, Mailtrap, or SendForensics let you test your content and sending reputation before going live. Think of it as a pre-flight checklist—catch issues before they take down your entire campaign.

CTRs Are Cute. But Click-to-Conversion Tells the Truth.

Clicks are nice. Conversions are better. It’s tempting to look at a 4.5% click-through rate and assume a campaign was a success, but unless you know how many of those clicks actually resulted in action (form fills, purchases, bookings, whatever your CTA was), you’re working with half the picture.

Click-to-conversion rate = (Number of conversions ÷ Number of clicks) x 100

It tells you if your email and your landing page worked together. If you had 100 clicks and only 2 conversions, congrats, you’re hemorrhaging interest somewhere in the middle.

Questions to ask when click-to-conversion is low:

• Is the CTA crystal clear and repeated?

• Is the landing page mobile-optimized?

• Is the offer or content gated unnecessarily?

• Is the user experience consistent from email to page?

Also, here’s a tip that’s often overlooked - stop linking to your homepage unless it’s part of the strategy. Every email needs a purposeful next step.

Engagement Quality > List Quantity

Bigger isn’t better when it comes to your list. A bloated list with 20,000 barely-interested subscribers will cost you more (in platform fees and deliverability hits) than a well-nurtured list of 2,000. Email service providers are watching how your audience responds—opens, clicks, scroll depth, read time—and they adjust deliverability accordingly. If most of your list ignores you, inbox providers start ignoring you, too.

Clean, segmented lists win. Here’s what to do:

• Prune your list quarterly. If someone hasn’t opened or clicked in 6+ months, sunset them or launch a re-engagement flow.

• Use behavior-based segmentation. Trigger emails off past clicks, time since last purchase, cart behavior, etc.

• Let people manage their preferences. Some subscribers don’t want weekly promos—but they might love your monthly tips.

More than anything, get comfortable with the idea that unsubscribes aren’t failures. They’re list hygiene in action.

The Hidden Goldmine: Revenue Per Email Sent (RPE)

Here’s a juicy one most marketers overlook: revenue per email sent. It’s a simple formula that packs a punch.

RPE = (Total Revenue from Campaign ÷ Total Emails Sent)

It tells you what each email is worth—which helps with budgeting, forecasting, and figuring out which campaigns are actually driving the bottom line. It’s particularly useful for eCommerce brands, but works just as well for lead-gen and SaaS.

Let’s say Campaign A had a 2% click rate and made $6,000 on a 20,000-send.

Campaign B had a 1% click rate but made $9,000 on a 10,000-send.

Guess what? Campaign B is crushing it in terms of efficiency. You just wouldn’t see that if you were only looking at clicks.

Bonus Metrics That Deserve Your Attention

We’ve covered the heavy hitters, but if you want to graduate from Email Marketing 101, here are a few more metrics worth tracking:

• Time to Click: How quickly are users clicking after receiving? This can help optimize send times.

• Read Rate: Tools like Litmus can help you see how long someone spent reading. Did they skim or actually consume?

• Device and Client Breakdown: Knowing your audience is mostly mobile? That changes everything from subject line length to CTA button size.

It’s Not the Metrics - It’s What You Do With Them

Here’s the truth no dashboard can show you: metrics are only as good as the actions they inspire. It’s easy to become a data hoarder, drowning in charts and KPIs without changing a single thing about your strategy.

The smartest email marketers aren’t chasing high numbers. They’re chasing useful patterns—and constantly optimizing based on what those patterns reveal.

If your goal is sustainable ROI, trust, and long-term brand equity, shift your focus:

• Stop worshipping opens.

• Start understanding deliverability.

• Trade generic blasts for segmented flows.

• Prioritize clarity, context, and conversions.

Because in this inbox-saturated world, sending emails isn’t the hard part. Sending emails that actually work—that’s the craft.