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Updated! For the latest email client popularity analysis, view our latest report.

It’s been close to two years since I last dived into our client data to see what’s been happening. For those not familiar with these numbers, every time one of your subscribers opens an email you’ve sent, we record which email client they were using. This makes it easy to see which email clients your subscribers are using, and more importantly which email clients you can forget about testing in.

Given how long it’s been since we looked at the numbers, I decided to compare the stats across all email clients for every month since May 2009. Here’s the 2011 report if you’re interested in the complete stats. One new thing I tried this year however, was to group each client into desktop, web and mobile – hoping to see if any trends on how people are using email emerged. After crunching the numbers from a little over three billion email recipients, here’s how it looked:

Email client usage across desktop, web and mobile 2009 - 2011
Incredible. While I expected mobile email usage to be on the rise, I didn’t anticipate such agressive growth. Mobile email clients like the iPhone, iPad and Android have grown from 4% of the market to almost 20% in just two years. Interestingly, it’s been predominantly at the expense of the desktop market. Desktop email clients like Outlook, Thunderbird and Apple Mail have lost 11% in the last two years. Web-based market share has remained relatively unchanged in the same period, losing around 4% of the market.

Breaking down the mobile market

The mobile email world was very different two years ago. The iPhone 3G was starting to make a name for itself, while the iPad and Android had only just been released. The Palm Pre was still months away and Windows Mobile 6.1 was the latest phone OS from Microsoft. The bulk of BlackBerry phones on the market didn’t support HTML email at all. Mobile email clients accounted for just 4.16% of all activity we tracked and the iPhone was responsible for more than 95% of it.

As the chart above shows, mobile email has exploded since then. When we look at the activity across more than three billion emails, one in five is read on a mobile device. Looking at the latest data from May 2011, here’s the breakdown of market share across these email clients.

Mobile email client market share June 2011

It’s worth noting that both BlackBerry and Windows Phone are the only mobile email clients that block images by default. All iOS devices, along with Android and Palm WebOS automatically render images in HTML email. This can have an impact on how this data is gathered, which I’ll explain in more detail below.

It’s time to give this your attention

For the last five or so years, email design has really been all about “close enough”. With email clients like Lotus Notes and Outlook 2007, pixel perfection has been more or less a pipe dream. You get your template looking close enough across all the big email clients, and walk away somewhat satisfied (satisfied, but with a bad taste in your mouth).

The good news is that all smartphone email clients have great CSS support, far superior to many desktop clients. Your design will work in them. The question you have to ask yourself—is that good enough? For many on a small budget it may well be. But, the rise of mobile email presents an opportunity to give many of our subscribers a better email experience. A design built for desktop reading doesn’t often translate well to a much smaller screen.

More good news—it’s not hard. Here’s a simple walkthrough of a recent email redesign we did that focused on giving our mobile email readers a great experience too. Through the use of a few @media queries, you can even rework an existing template design to give your mobile email subscribers a design built just for them. It’s time to start optimizing.

How we measure this data

To find out what email client somebody is using, they need to open the email with images enabled. Some email clients (like Outlook and Gmail) block images by default and require an action by your subcriber to enable them. Other clients (like Apple Mail and the iPhone) do not. This can skew the market share upward a little for those that show images by default. What this doesn’t impact however, is change in share over time. The only time the accuracy of that change is impacted is when the default image blocking behaviour of an email client changes. This hasn’t been the case for any popular email client in the last two years, so it’s really the best way to keep a finger on the pulse of where email usage is heading.

This blog provides general information and discussion about email marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.
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