7 more ways to measure success in a marketing email


Kristina Lauren

We’ve explored some common email metrics you should definitely be keeping track of on our blog before, but today we’re going to dive into a few more that you may not have considered. The following seven email marketing metrics will give you a deeper understanding of how your subscribers are interacting with your campaigns and set you up for success. Let’s begin!

Click-to-open rate (CTOR)

This metric is very similar to the click-through rate, but the differentiation is that while click-through rate is the number of clicks an email receives from the number of emails delivered overall, CTOR is the number of clicks that come from the number of opens.

For example, let’s say you send an email to 1000 of your subscribers and 500 of them open it. Let’s also say that 200 people click-through to your website (because your product and call-to-action are truly spectacular!). To get your CTOR, you would take the amount of clicks (200) and divide it by the amount of opens (500), which in this case would give you 40%. On the other hand, your overall click-through rate would be 20%.

Tracking CTOR gives you a more detailed view of your email engagement compared to click-through rate. While both are incredibly useful, CTOR tells you if the subscribers who actually read or at least skimmed through your email felt engaged enough to click through to your website. If this rate is high, you’re doing something right. However, if the information or the offer within the email isn’t enticing enough, or worse, misleading based off of the subject line, then you may need to try something different.

To calculate your CTOR, use the formula below:

(Number of emails clicked / number of emails opened) x 100

Inbox rate

Your inbox rate tracks how many of your delivered emails manage to make it into your subscribers’ inboxes. Make no mistake, this isn’t the same as your delivered rate which, as the name suggests, simply measures how many of your emails were delivered. The reason why these metrics are different is because an email can wind up in the spam folder as well as your subscriber’s inbox and still count as a delivered email.

Of course, the goal for this metric should be 100%, but that may not always be possible for a number of reasons—spam triggers within your email, sending too many emails, or a lack of opens over time from your subscribers. If your inbox rate starts dipping below 90%, it’s time to reassess.

Use this formula to calculate your inbox rate:

(Number of non-spam emails delivered / number of emails delivered) x 100

Return on investment

Also known as ROI, this metric is a measure of how profitable your emails are in relation to the amount of money you’re investing. While it’s a huge indicator of how effective your email marketing efforts are, it can be somewhat difficult to track. But you can get a decent estimate by looking at how much your sales increase after a particular email is sent out or even by giving subscribers a unique code to use to save on an order. To track your costs, look at the costs of email-related software as well as the hours you and your team are spending on email. On average, email marketing can generate as much as $36 for every $1 spent, which is equivalent to 3600% ROI. So, how do you calculate your email ROI?

Use the formula below:

((Gain from investment - Cost of investment)/Cost of investment) x 100

Revenue per email

Revenue per email is essentially the amount of money that is generated per individual email.

You can track this metric using email clicks, your site traffic, and conversion rates.

Calculating this can tell you a few things. For one, it lets you know what kind of emails are resonating with your subscribers as well as what aspects of your emails could be bringing in more customers. It can also allow you to make revenue predictions based on previous email results.

However, if your revenue per email rate is on the lower side, you’d want to take a look at how you’re presenting your content and whether you’re sending the right content to the right audience. We always suggest looking at revenue per email on a campaign basis as well as in aggregate, as some campaigns will skew the data. For example, abandoned cart emails tend to have very high revenue per email, especially compared to a typical promotional email or newsletter.

Figure out your revenue per email amount using this formula:

(Revenue generated / number of emails sent)

Revenue per subscriber

This one’s similar to revenue per email, only we’re calculating the amount of money generated from your subscribers. Your revenue per subscriber can let you know if your subscribers are consistently turning into customers, or if they’re more so just passive onlookers of your brand.

One way to improve your revenue per subscriber rate is to make sure you’re engaging your subscribers with the content they want, and you can do this quite effectively by personalizing emails according to what your subscribers have displayed an interest in. Check out one of our posts on the subject of personalization.

Here’s how you calculate your revenue per subscriber:

(Revenue generated / number of active subscribers)

Subscriber acquisition cost

Do you use paid ads to acquire more subscribers? If you do, you’ll want to keep track of this metric. Just as you probably already monitor how much it costs you to acquire a new customer, focusing primarily on the cost of a new subscriber is just as important. Email may be quite inexpensive compared to your other marketing channels, but keeping track of how you’re gaining new subscribers can tell you a lot about where you should be focusing your efforts.

Maybe you get more form fills on a certain landing page, so it would make more sense to focus your advertising efforts on bringing even more traffic to that destination. However, if you also gain a decent amount of subscribers through giveaways, you’ll also want to take that cost into account.

To calculate this metric, use the formula below:

(Advertising cost/number of subscribers)

It would also be helpful to calculate this expense over different periods of time, especially to see how much it’s costing to bring in your newest subscribers.

Forwarding rate

This is the number of subscribers who are sharing or forwarding your emails. While this metric may not be one of the more crucial ones to look after, it can still tell you a lot about how passionate your subscribers are about your content and about how sharable it is.

It’s also a nice and easy way to grow your email list since it means that people who already have faith in your brand are advocating on your behalf, and, in most cases, they’re doing it for free. However, you can also incentivize your subscribers to share your emails more by giving them some kind of reward.

So, how do you actually track forwards? If you are able to see a detailed view of your opens and notice that one particular subscriber has opened your email several times within a short period of time, you can assume that the email was forwarded. However, most ESPs will also allow you to include a “Forward to a Friend” link within your emails. When your subscriber clicks on this link, they’ll be directed to a form that will prompt them to enter the email addresses of the people they want to forward the email to.

To calculate your forwarding rate, use this formula:

(Number of forwards/number of delivered emails) x 100


As you can see, there are a plethora of ways to measure success in your email marketing efforts, but at the end of the day, you should choose metrics that are going to be most valuable in improving your campaigns. If the process of figuring this out still seems a bit overwhelming, Scalero can help you narrow things down. As experts in email automation, design, and strategy, our team will work with you to bring your email marketing vision to life and set you on the right path for success. Contact us today to get started!

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