Email metrics provide critical, quick feedback for a campaign. This is key because most opens and clicks occur within 72 hours after a send.

But measuring opens and clicks is often just scratching the surface of the actual performance of a campaign. In this post, I’ll compare three traditional email marketing metrics to newer, more meaningful ones.

Open Rate vs. Open Rate Churn

Many email practitioners believe open rates are misleading. There are several reasons for this. First, for an “open” to register, the recipient of the email must download an image. Depending on the content and type of email, recipients who actually open and read it may never need to download images. Also, some preview screens will allow recipients to read an email without opening it.

Thus, open rates are oftentimes higher than what is reported. Despite this, the open rate has stuck around as the most popular benchmark for email engagement.

When I look at open rates across an email program, it’s important to understand who is opening. If a program consistently has a 15 percent open rate, does that mean the same 15 out of 100 people open every email? Or is it a new group of recipients each time? The answer is likely somewhere in the middle.

I call this the “open rate churn.” It’s the percentage of recipients who open every email versus those who seldom do.

Analyzing the open churn rate will produce a more complete picture of the overall engagement of a subscriber list. It will help determine the offer and frequency, too.

Read more: 3 Email Marketing Metrics for Mobile, Multi-device Consumers