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Gasp! We’re baring it all and exposing our open rates

Hello Friend,

Have you ever been to the beach and there’s that hairy guy with a big gold chain, wearing a speedo and showing just a little too much? 
For the faint of heart, turn away now because…

…this week’s email is all about open rate data. I’ll show you ours, ask to see yours, and I’ll cover a key metric: the email open rate, which is one way to gauge whether your users are engaging with your emails.

Most companies don’t write interesting emails. Just take a look at averages across industries.

Mailchimp publishes “Email Marketing Benchmarks”. Averages across different industries vary, but most industries have between 10 and 20% open rates on their marketing emails. The top industry is a mysterious “Other” with a 33.52% open rate.

I’m feeling a little nervous sharing this… but here are our email open rates for the past few emails.

Open rates on Customerio emails

We started off with a rate of 33% opens, equal to Mailchimp’s best performing industry segment. But by applying the advice experts have been giving and incorporating feedback from you, we’re now at open rates of 47% — nearly a 30% improvement!

If you’re relying on open rates as a key metric, it’s important to understand how they’re calculated.

So, how does almost every email provider calculate open rates?

A tiny invisible image, unique for every recipient, is placed somewhere in the email. So, when you send an email to and the image is accessed from the server, you know Tyrion opened the email. This works the same way across almost all email products. 

Tracking using an image works great except for one tiny problem…

Gmail turns images off by default and so do a few other email clients. As a result, open rates tend to be under-reported.

For example: A friend of mine runs Timehop (an awesome startup that sends a daily email about what you did on that day a year ago). They have A LOT of gmail users who also use iPhones. If these people receive the email before they get to work, there is a good chance they’ll open the email on their iPhone.

Here’s the tricky part: iPhones automatically load images. So their open rates report higher when the emails are sent early in the morning. But it would be wrong to conclude that more people are reading the emails.

Moral of the story: take the accuracy of open rates with a grain of salt. 

Consider where people will be when they receive your email, and what device they use to read your emails.

Do you get killer open rates on your emails?

Forward an example of one of your highly performing emails to It’ll just be between you and me unless you tell me:

  1. You want me to feature it on
  2. I can share it in the newsletter next week.

Do your open rates need improvement?

Great, let’s work on it together. Forward me an email you wish had performed better. Don’t forget to include some context about what purpose that email should have served.

Next time, I’ll share some common traits of high performing emails that we will all be able to learn from to kick our emails up a notch.

Before you move on to surfing reddit, hacker news or maybe doing some work, do me a huge favor. 

Forward ONE email you currently send to Let me know if it’s “killer” or “needs improvement”.

Until next time,


P.S. A few days ago I did a blog post about how I would re-write an email for Trello to improve readability. They read it and changed the email they were sending. My top tip is to set the width of your text emails to 550px max

I recently made that change on all of our text emails.