Email marketing is one of the most powerful tools available to brands, but success isn’t just about sending more messages—it’s about measuring the right things and optimizing based on what the numbers are telling you. Metrics and analytics give you a window into your audience’s behavior, letting you see what’s working, what’s not, and where you can improve.
Analytics are essential for understanding whether your emails are truly performing. Monitoring your metrics in Klaviyo on a monthly basis is critical — both to catch technical issues early and to track what’s driving results.
On the technical side, problems can easily slip through unnoticed. For example, a Shopify theme update may cause your popup form to stop displaying, or an abandoned cart flow may fail to trigger due to a broken integration. Without regular monitoring, these issues can persist for weeks, costing brands tens of thousands of dollars in lost revenue.
The second reason to track analytics consistently is strategic: to understand what your subscribers actually care about. Analytics reveal which emails, offers, and content are driving conversions — allowing you to double down on what works and cut out what doesn’t. In short, analytics aren’t just numbers; they’re insights that protect your revenue and fuel smarter decisions.
Let’s break down the most important email marketing metrics, what they mean, and how you can use them to drive better results.
1. Open Rate
Open rate measures the percentage of recipients who open your emails, calculated by dividing unique opens by the total number of delivered emails. Since the release of Apple’s Mail Privacy Protection (MPP) in iOS 15, open rate has become an unreliable performance metric. The reason for this is that MPP artificially generates “opens” for Apple Mail users, inflating the numbers and masking true engagement. So if you see 60–80% open rates in Klaviyo, that’s not reality — most of those “opens” are being triggered by Apple’s privacy bot.
This inflation distorts A/B test results and undermines any automation triggers that rely on opens. That’s why open rates should no longer be treated as a measure of engagement or success. Instead, they should be used only as a diagnostic tool.
Here’s how:
- If your reported open rates fall below 30%, that’s a strong indicator of a deliverability problem — because even inflated numbers should be higher.
- If your open rates exceed 80%, that doesn’t necessarily mean you’re safe. It could simply reflect MPP’s inflated activity.
When diagnosing deliverability, the best corrective action is to narrow your sending audience to your most engaged subscribers — people who have clicked an email in the last 14 days. Sending only to this high-engagement segment should generate open rates above 90% and click rates above 10%. These signals tell inbox providers that your emails are wanted, improving your sender reputation and strengthening inbox placement over time.
2. Click Rate
Click rate measures the percentage of people who clicked a link in your email, based on the total number of recipients who received it. This is different from click-through rate (CTOR), which measures clicks only against the people who actually opened the email. In Klaviyo’s dashboard, what you see reported is click rate — clicks as a percentage of all delivered emails, not just opens.
As of 2025, click rate is the number one indicator of engagement. It answers the most important question: Do people care about what you’re sending? Every email should provide value, and strong click rates signal that your messaging, content, and offers are resonating. Conversely, low click rates are a red flag that your emails aren’t capturing attention or driving action.
Click rate is also the primary indicator of deliverability health in 2025. For example, if you see open rates above 60% but click rates as low as 0.05%, it’s a clear sign that your open data is inflated by Apple Mail’s MPP “bot opens,” while real engagement is lacking. In other words, your deliverability is suffering even if opens look high.
To gauge performance, compare your click rates against benchmarks for your industry. If your numbers fall short, it means your content, offers, or targeting need adjustment. Ultimately, optimizing for click rate keeps your campaigns focused on real human engagement, not inflated vanity metrics.
3. Unique Clicks
In Klaviyo, a unique click represents the number of individual subscribers who clicked on a link in your email or SMS, regardless of how many times they clicked it. This makes it a subscriber-centric metric: each person is only counted once, even if they click multiple times. Unlike total clicks, which measure the total number of clicks across all links (including repeats from the same subscriber), unique clicks provide a clearer picture of how many distinct people engaged with your content. This distinction is important because unique clicks serve as one of the most reliable indicators of genuine engagement, especially in the post-MPP landscape where open rates are inflated.
A high unique click rate shows that your content, offers, and calls-to-action are compelling enough to inspire action, while a low rate signals that your messaging may need refinement. Tracking unique clicks also helps identify which campaigns, offers, or designs are most effective, supports list hygiene by flagging disengaged subscribers, and enables smarter segmentation by showing you exactly which audience segments are the most responsive. In short, unique clicks go beyond vanity metrics to show you how many real people are taking the next step with your brand.
4. Placed Order Rate
In Klaviyo, Placed Order Rate is the percentage of recipients who placed an order after receiving a specific campaign or flow email. While it’s normal for this metric to be relatively low in campaigns, it remains one of the most important KPIs because it tracks the ultimate outcome: sales generated from your emails.
In fact, for flows, placed order rate is often considered the north star metric — the single most important measure of success. This is because flows (like a welcome series or abandoned cart flow) are sent to people who are all at the same stage of the customer journey, making it easy to compare performance “apples to apples.” For example, in a welcome series, every subscriber receives the first email exactly one day after joining, so placed order rate directly reflects how persuasive that message is at driving conversions.
By contrast, campaigns are sent to larger, more varied audiences — some who purchased last week, others who haven’t purchased in months — which makes placed order rate less reliable. That’s why campaigns are typically optimized for total revenue instead.
Another important factor is Klaviyo’s 5-day attribution window: orders are attributed if they occur within 5 days of either opening or clicking the email (or longer, if you’ve adjusted the attribution settings). This means it’s essential to wait at least 5 days after sending before evaluating placed order rate or attributed revenue, otherwise you risk underestimating performance.
In short: for flows, placed order rate is your north star metric, because it shows how effectively each touchpoint moves customers toward purchase. For campaigns, focus on overall revenue while still keeping an eye on placed order rate as supporting context.
5. Unsubscribe Rate
The unsubscribe rate is the percentage of recipients who choose to opt out after receiving an email. Monitoring this metric on a monthly basis is critical because a steadily rising unsubscribe rate is usually a sign of misalignment between subscriber expectations and the actual experience your emails deliver.
Subscribers live in crowded inboxes, receiving dozens of brand emails daily. If your content doesn’t provide real value or fails to meet their expectations, unsubscribes are inevitable. That’s why understanding your audience and tailoring your messaging is so important.
Benchmarks:
- Healthy: 0.2–0.5%
- Warning: Above 1%, depending on industry
How to improve:
- Set expectations upfront (how often subscribers will hear from you).
- Balance promotions with educational or entertaining content.
- Offer a preference center so people can reduce frequency instead of unsubscribing.
6. Bounce Rate
Bounce rate measures the percentage of emails that fail to reach recipients’ inboxes, compared to the total number of emails sent. High bounce rates are a red flag for inbox providers like Google and Yahoo because the assumption is that any reputable sender knows who they’re sending their emails to. This damages your sender reputation and reduces deliverability.
There are two types of bounces:
- Soft Bounce: Temporary delivery issues such as a full inbox or a temporary server error.
- Hard Bounce: Permanent issues, like invalid or non-existent email addresses. Hard bounces are especially harmful to your sender reputation.
To maintain healthy deliverability, your bounce rate should stay below 1%. If it starts creeping above that threshold in your campaigns or flows, it’s a clear sign you need to take action. Regular list cleaning is critical — use a sunset flow to remove unengaged subscribers and always send campaigns to engaged segments only.
For example, if someone has been on your list for two years without opening an email, chances are their address is inactive and continuing to send to them only increases bounce risk. By keeping your list clean and focusing on engaged contacts, you protect your sender reputation and maximize inbox placement.
Benchmarks:
- Under 2% is standard
Why it matters: High bounce rates hurt your sender reputation and may signal poor list hygiene.
How to improve:
- Regularly clean your list of invalid addresses.
- Use double opt-in to prevent fake signups.
- Monitor bounce reports from your ESP.
7. Spam Complaint Rate
Your spam complaint rate is the percentage of recipients who mark your emails as spam. This is the single worst signal you can send to inbox providers, because when someone reports your email as spam, they’re essentially saying: “I don’t know this sender, and I don’t want these emails in my inbox.” As a result, even a small spike in complaints can severely damage your sender reputation and inbox placement.
To stay safe, your spam complaint rate should remain below 0.1%. If it rises above that threshold, two common causes are usually to blame:
- Overloading subscribers with promotions. Too many sales-heavy campaigns without enough value-driven content often push people to hit “spam.”
- Emailing people who never opted in. Some brands use tools like Retention.com to capture visitor emails and start sending campaigns, even if those visitors never subscribed. While tempting, this approach dramatically increases spam complaints and long-term deliverability risks.
Monitoring and keeping your spam complaint rate low is essential, especially if you’re using enrichment tools or sending frequent campaigns. A clean, permission-based list and a balanced content strategy are the best defenses against spam complaints.
Definition: The percentage of recipients who mark your email as spam.
Why it matters: Even small numbers can be devastating for deliverability.
Benchmarks:
- 0.1% or lower is acceptable
- 0.3%+ is excessive and can lead to filtering or blocking by Gmail, Yahoo, and other inbox providers
How to improve:
- Only email people who explicitly opted in.
- Make unsubscribe easy and visible.
- Avoid spammy words and deceptive subject lines.
8. Pop-up Form Opt-in Rate
The single highest-leverage action any e-commerce brand can take to boost email marketing revenue is to get more people onto their list. If you’re already investing in ads and driving traffic to your site, you must maximize that investment by converting as much of that traffic as possible into subscribers. The key metric to watch here is your pop-up form opt-in rate — the percentage of visitors who join your list divided by the total number of people who see the form.
Klaviyo considers an opt-in rate above 3% to be excellent, but ambitious brands regularly achieve 7–9% or higher by relentlessly optimizing. The path to these results is simple: A/B test your pop-up every single month. Test offers, form designs, copy, and timing. Review your results, implement what works, and set up the next test immediately.
Your pop-up opt-in rate should be one of your most closely monitored metrics. If you’re converting below 7%, improving your form should be a top priority. Every percentage point gained here compounds across all your campaigns and flows, fueling long-term revenue growth.
9. Net List Growth
Net list growth measures how many new subscribers you’ve truly added to your email list in a given month. It’s calculated as the total number of new subscribers minus unsubscribes, bounces, and any suppressed contacts from list cleaning.
Net List Growth=New Subscribers−(Unsubscribes+Bounces+Suppressions)
Example:
- 500 new subscribers in a month
- 120 unsubscribes
- 30 bounces
- 0 suppressions
500−(120+30+0)=350 net new subscribers
This metric gives you the clearest picture of whether your list — and therefore your revenue potential — is growing or shrinking. For healthy, sustainable email marketing revenue, your list must grow steadily with subscribers who are genuinely interested in your brand. Without consistent net list growth, your revenue plateaus, because even the best flows and campaigns can only perform as well as the audience you’re reaching.
Your pop-up form opt-in rate is usually the biggest driver of this growth. If your analytics show slowing or negative net list growth, it’s a signal to double down on optimizing your forms through A/B testing and stronger offers. In short: list growth equals revenue growth. A strong, expanding list is the engine that powers everything else in your email marketing strategy.
10. Prospect to First Time Purchase Conversion Rate
Prospect-to-First-Time Purchase Conversion Rate measures the percentage of new email subscribers who make their first purchase within 30 days of signing up. If your list is growing but those subscribers aren’t converting into buyers, then list growth is nothing more than a vanity metric. What truly matters is how effectively you’re turning site visitors into paying customers.
This is a high-leverage metric because it shows how efficiently you’re converting prospects into first-time buyers — and directly reflects the strength of your return on ad spend (ROAS). The better this number, the more profitable every dollar spent driving traffic to your site becomes.
Formula: New Purchasers within 30 Days/New Subscribers×100
Example:
- 500 new subscribers in a month
- 50 of them make a first purchase within 30 days
(50÷500)×100=10% conversion rate
Prospect-to-First-Time Purchase Conversion Rate — Benchmarks
| Industry / Context | Typical Range |
|---|---|
| General e-commerce (new visitors) | 2% – 5% Pipedrive+10Opensend+10Digital Web Solutions+10 |
| First-time buyers (standard products) | 2% – 5% Opensend |
| High-performing stores | 5%+ Opensend |
| Financial services (accounts / offers) | 4% – 10% Opensend |
11. A/B Test Analytics
In Klaviyo’s Experiments tab, you can track all the A/B tests running across your campaigns and flows. Each month, review the results from your previous tests, extract key insights, and use them to shape your next round of experiments. The goal is to create a continuous cycle of testing and optimization. By focusing on high-leverage elements — like subject lines, offers, CTAs, or popup forms — you’ll consistently improve engagement metrics and, more importantly, drive sustainable, profitable revenue growth.
🔑 High-Leverage Elements to A/B Test First
- Subject Lines & Preview Text – The first thing subscribers see, directly affecting open opportunities (and therefore clicks & revenue).
- Offers & Incentives – Discounts, free shipping, bundles, or loyalty perks — the biggest driver of conversions.
- Calls-to-Action (CTAs) – Button text, placement, and design have an outsized effect on click rates.
- Email Timing & Send Cadence – When and how often you send can dramatically influence engagement and unsubscribe rates.
- Content Personalization – Dynamic product recommendations, conditional blocks, and targeted messaging.
- Popup Forms – Headlines, offers, imagery, and timing directly impact list growth (the foundation of revenue).
- Email Design & Layout – Hero image vs. grid, long-form vs. short-form, and mobile responsiveness.
📌 Start with subject lines, offers, and CTAs — these three typically deliver the fastest, biggest wins.
Final Thoughts
Tracking email metrics isn’t about obsessing over numbers—it’s about understanding what those numbers mean for your audience and your strategy.
- Open rate shows curiosity.
- Click rate and CTOR show engagement.
- Unsubscribes and spam complaints show alignment (or lack of it).
- Bounce rate shows list quality.
- Replies show trust.
When you look at all these metrics together, you can make data-driven decisions that improve your deliverability, strengthen your customer relationships, and ultimately drive more sales.
