Email marketing performance: key metrics to track

Sending emails is an increasingly common strategy in digital marketing. Its return on investment (ROI) is estimated at 28.5%. Around 35% of marketers send 3 to 5 emails to their customers each week. Email marketing helps attract new leads while also nurturing existing customers.

After launching an email campaign, it's essential to analyze its performance. Why? To use the results to improve future campaigns. In this guide, we take a look at the key email marketing KPIs you should be tracking.

Deliverability rate

In France, the average email marketing deliverability rate is around 95%. It’s the starting point for all other email KPIs. This rate tells you the percentage of recipients who actually received the email.

Deliverability rate = (number of delivered emails / number of emails sent) × 100

How to improve your deliverability rate

To increase your deliverability rate, follow these best practices:

reduce the number of invalid or inactive email addresses
stop instant subscriptions
avoid your emails being marked as spam
make the unsubscribe process easy
personalize email content as much as possible

Open rate

The open rate shows whether the emails you sent were actually opened. The higher it is, the better your campaign performance. This rate can vary based on the day and time of sending.

Open rate = (number of opens / number of emails sent) × 100

How to boost your open rate

Focus on optimizing the subject line and pre-header—these are the first elements your recipients see in their inbox. They can either encourage or discourage people from opening your emails. Make them as compelling as possible.

Another tip: avoid using “noreply” sender addresses.

Also, personalize send times based on your audience’s habits. Generally, the best day to send marketing emails is Saturday, with an average open rate of 45.2%. Friday ranks second (40.7%), followed by Tuesday (38.7%).

Good to know: Top 5 industries with the highest open rates

Hardware – 46.8%
Health and wellness – 44.7%
Travel – 44.5%
Wine and spirits – 44.3%
Culture – 43.7%

Click-through rate (CTR)

The click-through rate reflects the percentage of recipients who opened your email and clicked on at least one link. It’s a strong indicator of engagement with your email content.

CTR = (total number of link clicks / number of emails sent) × 100

How to improve your CTR

write a clear, simple subject line
create content that encourages clicks
highlight your call-to-action (CTA)
include visuals

Good to know: Top 5 industries with the highest CTRs

Hardware – 5.4%
Gaming – 4.8%
Culture – 4.6%
Fashion – 4.2%
Home décor – 3.7%

Bounce rate

The bounce rate represents the percentage of emails that failed to be delivered. There are two types of bounces:

Soft bounce: caused by temporary issues like a full inbox or server errors
Hard bounce: caused by permanent issues like non-existent or deactivated email addresses

Bounce rate = (number of undelivered emails / number of emails sent) × 100

Brands should aim for the lowest bounce rate possible. To improve it, clean your database regularly.

Conversion rate

The conversion rate measures whether your campaign achieved its intended goals. It shows how many recipients:

visited your landing page (via a link or CTA)
completed the desired action (click, download, form submission)

Conversion rate = (number of conversions / number of emails sent) × 100

This KPI directly impacts your ROI. To improve it, use clear, clickable CTAs and make sure your audience is well-segmented.

Unsubscribe rate

This represents the number of people who clicked the unsubscribe link in your email. On average, it’s around 0.10%. It indicates how many recipients found your content irrelevant.

Unsubscribe rate = (number of unsubscribes / number of emails sent) × 100

To lower it, send relevant messages to the right subscribers and pay close attention to your email design.

Engagement rate (reactivity rate)

This KPI measures how engaged recipients are with your email campaign.

Reactivity rate = (number of link clicks / number of emails opened) × 100

Complaint rate (spam reports)

The complaint rate corresponds to the number of emails marked as spam by recipients. Your objective should be to keep this rate as close to zero as possible.

Spam complaints negatively impact your sender reputation. Too many complaints can result in future emails landing directly in spam folders.

Complaint rate = (number of complaints / number of emails sent) × 100