What Metrics Should You Be Using to Measure Email Marketing Campaigns?

By Jamie Gloyne, Persado Vice President, Global Consulting 

Reporting is an integral part of every marketer’s job. In an age when seemingly every marketing dollar spent is under scrutiny, executives want to know how programs are measuring up and whether goals are being met. But though numbers are supposed to be an objective, black-and-white way to measure effectiveness, there’s a whole lot of gray when it comes to email marketing metrics. Being able to decipher the pros and cons of various KPIs is necessary if marketers want to manage up and meet expectations. And which metric or metrics you focus on depends on the goal or objective of a campaign. A brand awareness campaign is different than one seeking to sell merchandise or get people to sign up for something. 

This guide defines the most popular and important metrics for measuring email marketing campaigns and gives the scoop on why they matter (and why they don’t tell the whole story). 

What metrics can be used to measure email marketing performance?

Many KPIs are available from Email Service Providers (ESPs) and website analytics tools and all have some purpose in evaluating the success of the whole or of specific parts of the email. Opens, click-through rates (CTRs) and conversions are the big ones, but other metrics like time on site, bounce rate, unsubscribes and delivery rates have their places in marketing metrics spreadsheets as well. First, determine the main objective. The KPIs should follow from that. 
Let’s look at some common goals and objectives after we’ve explained the metrics that are available. 

Advantages and disadvantages of focusing on email OPEN RATES  

Every email campaign should have an open rate, which as the term implies, measures the effectiveness of the subject line in persuading subscribers to open. It’s important to compare apples to apples when setting benchmarks, as not all campaigns are opened equally.  For a promotional campaign, an open rate around 10-20% is average, based on Persado’s research, whereas account-related emails such as password resets or shipping confirmations can expect up to 70% of consumers to open. 

While an email open on its own doesn’t generate any revenue, it’s important to always monitor because it’s the first step towards any kind of conversion goal. It also factors into sender reputation, which in turn contributes to deliverability and inbox placement calculations by email account providers such as Gmail and Yahoo. 

Often, we see that a small increase in open rate translates into a larger one in CTRs and conversions, meaning even an uptick from 12% to 14% open rate can have material value.  

Of course, an open rate can’t tell you anything about how successful the body content of an email is. 

Pros and cons of email CLICK THROUGH RATES

The CTR (measured as Clicks / Delivered) is usually the easiest way to determine the effectiveness of the body content of an email. CTRs vary depending on the type of campaign and the quality and relevance of the copy and creative. They can also be influenced by the subject line, even if nothing changes in the body.  

For that reason, the CTR is often the preferred engagement metric when evaluating both the subject line and body content. 

Dos and don'ts for email CONVERSION RATES 

Conversion rates are generally the holy grail of email metrics because they are the ultimate objective of most promotional and eCommerce emails. Depending on the campaign, conversions could mean purchases, sign-ups or leads generated. This important email marketing metric may have multiple steps, such as form pages in a shopping cart, so there could be intermediate conversion events leading up to the final, revenue-driving KPI. 
Normally if they’re available, this metric is the best measure of success for any email campaign with a conversion goal. 
The challenge with this metric is that, depending on the conversion rate and the size of the send (number of recipients), the numbers might be very small and therefore not a reliable indicator. For example, an email that generated 20 conversions can’t be hailed as conclusively better than an email with 15 conversions, because those numbers are too small. In other words,  the difference is not statistically significant. In this situation, it’s best to look at an intermediate conversion event or the CTR, whichever is closest to the final conversion and has sufficient data. 

Other email metrics to be aware of

Delivery Rate / Bounce Rate / Inbox Placement: Very important indicators of sender reputation. If you have a problem with these, look into list hygiene and frequency of sends to unengaged audiences. 
Unsubscribe Rate: Important to keep an eye on, but not largely affected by email content. Unsubscribe rates are more likely triggered by receiving too many campaigns. They should be calculated as unsubs/opens because it’s impossible to unsubscribe without opening. 
Average Order Value / Revenue: Important to the overall value of the email program, but less important than conversion rate. It’s generally better to have two subscribers spend $5 each than to have one spend $12. Why? Because if your product or service is good, customers will return. And, over time, your AOV will tend towards an average. There may be an occasional spike, but those are usually caused by one large purchase that is unlikely to be repeated (and may be fraud). 
Time on site: Useful where there is no conversion event, but CTR will usually suffice. 
Click-to-Open Rate (CTO): Usually you can ignore this because the CTR is more reliable in capturing the effectiveness. 

Open, click-through and conversion rates are popular email marketing metrics for a reason — though not perfect on their own, they paint a good picture of a campaign’s effectiveness. It’s important to first identify your objective. After that, use this reader’s digest guide to which metrics are the most important for the marketing email campaign. 

Brand Awareness:  Open Rate, CTR 
Promotional, eCommerce, Enrollment, Subscription Renewal, Welcome, Cart or Browse Abandon:  Open Rate, CTR, Conversion Rate
Account related (Password reset, shipping confirmation, account change notification):  Don’t spend too much time worrying about these. Just make sure they’re delivered. 

Total vs. Unique 
Generally, unique numbers are preferable to totals. After all, most subscribers are only going to convert once, no matter how many times they open or click. 

Bottom Line: No matter what you choose, the most important thing to remember is that your goals and KPIs are aligned.