In the world of email marketing, performance is everything. You might spend hours crafting the perfect message, designing a beautiful layout, or segmenting your list—but if you’re not tracking the right metrics, you’re flying blind. For small and medium-sized businesses especially, understanding what works and what doesn’t is key to getting the most value from every email sent.
This guide will walk you through the most important email marketing metrics, how to calculate them, and how to use them to improve your campaigns over time.
Why Metrics Matter in Email Marketing
Email marketing is one of the most measurable channels available to marketers. Unlike social or offline efforts, you can track almost every user interaction—from the moment an email is opened to the final conversion. But data only becomes valuable when you know what to look for.
By focusing on the right metrics, you can:
- Identify which campaigns are working
- Understand subscriber behavior
- Improve your email content and design
- Boost ROI by sending more targeted, effective emails
Key Email Marketing Metrics You Should Track
Let’s break down the most essential metrics and what they tell you about your performance:
1. Open Rate
This is the percentage of recipients who open your email. While open rates have traditionally been a go-to metric, privacy updates (like Apple’s Mail Privacy Protection) have made them less reliable. Still, they offer a directional view of subject line effectiveness.
Formula:
Opens ÷ Emails Delivered × 100
2. Click-Through Rate (CTR)
CTR measures the percentage of recipients who clicked on a link within your email. It’s a direct indicator of how engaging your content and CTAs are.
Formula:
Total Clicks ÷ Emails Delivered × 100
3. Click-to-Open Rate (CTOR)
This often-overlooked metric compares the number of unique clicks to the number of unique opens. It shows how compelling your content is after the email is opened.
Formula:
Unique Clicks ÷ Unique Opens × 100
4. Conversion Rate
This is where the rubber meets the road. Conversion rate tells you how many recipients took the desired action—like making a purchase or signing up for a webinar.
Formula:
Conversions ÷ Total Emails Delivered × 100
You’ll need proper tracking (e.g., UTM tags and a linked analytics platform) to measure this accurately.
5. Bounce Rate
This indicates how many emails couldn’t be delivered. A high bounce rate can hurt your sender reputation.
- Hard Bounce: Invalid or non-existent address
- Soft Bounce: Temporary issue (like a full inbox)
Formula:
Bounced Emails ÷ Emails Sent × 100
6. Unsubscribe Rate
A sudden spike here could signal that your content isn’t resonating, or that you’re emailing too frequently.
Formula:
Unsubscribes ÷ Emails Delivered × 100
7. Spam Complaint Rate
This metric is often ignored, but even a small number of spam reports can damage your sender reputation. Keep this well below 0.1%.
8. List Growth Rate
Not just about who’s leaving—this tells you how well you’re attracting and retaining subscribers over time.
Formula:
[(New Subscribers – Unsubscribes) ÷ Total Subscribers] × 100
9. Revenue per Email (RPE)
If you’re running ecommerce or lead-gen emails, this is one of the most telling metrics. It ties email performance directly to ROI.
Formula:
Total Revenue ÷ Emails Sent
Which Metrics Matter Most?
That depends on your goals.
- Want more engagement? Focus on CTOR and CTR.
- Need better ROI? Watch conversion rate and revenue per email.
- Improving deliverability? Monitor bounce and spam rates closely.
While open rate is still monitored, clicks, conversions, and list quality tell you far more about the effectiveness of your email marketing.
Commonly Undertracked But Powerful Metrics
Many marketers obsess over open rates but overlook CTOR and revenue metrics. That’s a mistake. Click-to-open rate, in particular, is a powerful indicator of how well your content resonates once someone actually opens the email.
How to Use These Metrics to Improve Campaigns
Tracking metrics is just the first step. Use the insights to:
- A/B test subject lines and CTAs
- Adjust sending frequency
- Personalize content based on past engagement
- Clean inactive subscribers to improve deliverability
With time, these small optimizations lead to significant performance gains.
Final Thoughts
Mastering email marketing metrics isn’t about watching every number—it’s about focusing on the ones that align with your goals. Whether you want to drive more revenue, reduce unsubscribes, or boost engagement, the right metrics help you get there faster.
With cmercury, you get a clear, real-time view of your email performance—plus actionable insights to help you do more with every campaign.Want to see how your email campaigns are really performing?
Try cmercury’s advanced analytics and take the guesswork out of email marketing.
Disclaimer: This blog post was created with the assistance of Human Content Creators, AI and Search tools to help collect information, plan content, and ensure accuracy. We strive to deliver valuable and well-researched insights to our readers.
Rijo Sam - Director, Customer Success
Rijo has over 16 years of experience in customer handling across various industries, including building offshore business intelligence databanks and leading digital marketing projects. He currently heads Customer Success at cmercury, where he has helped achieve a 98% customer retention rate and contributed over 20% of revenue through smart upselling. A popular product trainer, Rijo has conducted digital marketing workshops for more than 1,000 professionals. In his free time, he enjoys experimenting with local non-vegetarian recipes, often impressing family and friends with his culinary skills.