It’s 2022, and email is alive and kicking. In fact, the Digital Agency Network shares that a study by McKinsey & Company still finds email marketing to be 40 times more effective than social media. It’s because of this effectiveness, though, that the niche is so competitive.

Even with the best email optimization hacks, a fundamental understanding of key performance indicators (KPIs) is paramount to properly evaluating and adjusting campaigns. To help develop that, we’ve curated a list of the top KPIs to consider.

Key Performance Indicators for Successful Email Marketing

1. Email Sends

It's a simple, straight-forward KPI that tracks the number of emails sent, but analyzed over time, it can clarify what the optimal sending frequency and volume are for your audience and message.

2. Unique Open Rate

The number of opened emails is an excellent indicator of how well subject lines are attracting subscribers. Ongage recommends using this in the comparative analysis since it can be skewed the fact that emails in spam can still be counted as “opened,” while those whose images have not been viewed do not count.

3. Click-Through Rate (CTR)

This gives you an idea as to how often users click on links embedded in your email.

4. Conversion Rate

Conversion rates indicate how many people complete an action specific to campaign goals like registering for a webinar, purchasing an item, or signing up for a free trial. To increase conversion rates, make sure you have recurring call-to-actions (CTAs) telling users precisely what you want them to do.

5. Click-To-Open Rate (CTOR)

Calculated as the number of clicks divided by the difference of subtracting bounced emails from total sent emails. This is an important KPI specific to content evaluation and helps identify how effective your call-to-actions (CTAs) are.

6. Delivery Rate

This establishes how many of your actual emails are reaching subscribers — emails that haven’t bounced whether it’s due to being blocked by a spam filter or a full inbox, or due to your list having an email address that doesn’t exist.

7. Spam Complaint Rate

A particularly important metric, this indicates how many of your emails are being marked as spam. Too high, and your email may wind up blocked by the email platform.

8. List Growth Rate

Calculated as the total new subscribers minus both the number of unsubscribes and bounced emails, then the resulting difference is divided by the previous size of your subscriber list. A healthy email marketing approach should result in steady growth rates over time.

A Few Final Thoughts

Aside from looking at your overall return on investment per campaign, optimizing for mobile is another key consideration. The mobile market is proving lucrative and is expected to grow exponentially.

You’ll need to consider statistics below specific to this platform such as mobile open rate and mobile click rate, and test how well your content translates to being viewed on mobile devices like tablets and smartphones using portrait view.