Email is one of the most effective marketing channels, consistently able to drive high levels of traffic and conversion.

However if you’ve been running various campaigns, with different content, subject line variations and goals how do you know whether they’re successful or not? Can you be sure that any uplift is directly attributable to your last ‘brilliant’ email? Do you even know what you should be looking out for?

When planning any campaign, on any marketing channel, it’s vital that specific goals are outlined right from the start. As stated in our own Email Marketing Best Practice Guide marketing efforts can only be improved upon if results are compared with your intended goals.

So any areas where you can clearly see improvement can be highlighted and paraded around your office as a massive win. Areas that have underperformed can then be looked at and improved upon next time.

To help you figure what you should be measuring, here’s a list of key performance indicators (KPIs) for email marketing.


Although for the most part conversion tends to mean completed sales, particularly in regard to ecommerce, conversion can actually mean any action completed thanks to the email activity. For instance a newsletter subscription, a mobile app download, a whitepaper download, a survey filled in.

The conversion rate is simply the percentage of email recipients who completed a desired action after clicking on a link in your email.

Open rate

This is the amount of recipients who opened your email. The KPI itself doesn’t go deeper than that, it possibly just suggests that your subject line worked. It doesn’t mean that your email didn’t immediately go in the bin or marked as spam. Some email clients such as Hotmail automatically opens email as you scroll down your inbox, so again it’s not terribly reliable.

Click-through rate

Divide the amount of clicks on links within your emails with the number of emails delivered, then times by 100 and you have a click-through rate percentage. If it’s high than it means your content is working and you have strong calls-to-action.

Unsubscribe rate

The amount of recipients who have had enough of your emails and have hit ‘unsubscribe’. It’s important to manage email unsubscribes properly. The unsubscribe button needs to be clearly positioned and should be ‘one-click’. Making it easy for users to unsubscribe is far better than the other alternative…

Spam complaint rate

The amount of recipients who just hit the big spam button. Obviously you want this to be low. Unfortunately your emails don’t even need to be that ‘spammy’ for users to click the spam button, its often just used as a short cut to unsubscribe. The key is to make your subject lines as compelling as possible and not to bombard your recipients.

Bounce rate

The percentage of undeliverable mail. This can be split into two categories: Hard and Soft.

A hard bounce happens when an email address is wrong, these addresses should be removed immediately. A soft bounce happens when there’s a temporary delivery problem. Perhaps an inbox is full, or a server is down.

Delivery rate

Simply the amount of emails sent vs. the amount of emails delivered. This reveals much abut the quality of your email address list and the effectiveness of how your accrued these email addresses in the first place.

Site traffic

As emails are frequently opened on mobile devices while on the go, it’s possible that recipients open your message read it, then visit your site later on another device or desktop. Look for general increases in traffic in the time after you’ve sent an email. It’s not a precise measurement, but can be an indication of general behaviour.

Time on site

Precisely how much time a recipient then spends on your site after clicking-through on your email.

Average time before purchasing

How much time has passed between a recipient beginning to receive your emails and an eventual purchase? This could theoretically be any amount between a few hours to a whole year.

List Growth

If you stick to the same email list, then it will eventually shrink as customers naturally move away from your messaging and products. It’s important to continuously grow the amount of subscribers you have. This can be done through various incentives, contests, cross-promotions and simple newsletter sign-up widgets on your site.

Total sales

Don’t just measure the items successfully purchased that were featured in the email, include all of the items that a customer proceeded to buy while on site. Similarly, if the items in the marketing email weren’t purchased but others were after clicking through, include these in your measurement.

Cost savings

How much is an email marketing campaign saving your company compared to other campaigns on different channels?

Cost per lead

How much is it costing you on average to acquire each new customer or conversion?

Social growth

Perhaps you’re using email marketing to beef up the numbers of one of your social channels. Follower growth on any channel can be measured accurately.

Brand awareness

Emails are a fantastic way to keep your brand in a customer’s mind even when they haven’t purchased anything from you from a while. Even thought they may be emotionally unsubscribed, because they haven’t actually clicked unsubscribe means they may still buy something from you in the future. Unfortunately this is difficult to measure and is more of a beneficial soft metric of email marketing.

For more on email marketing download our Email Marketing Best Practice Guide and check out these 50 epic email marketing blog posts.

Our Festival of Marketing event in November is a two-day celebration of the modern marketing industry, featuring speakers from brands including LEGO, Tesco, Barclays, and more.

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