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It’s a little belated, but we’ve just completed analyzing email client usage across more than half a billion email opens throughout 2009. You can view the complete report here, but I recommend reading on as I expand on some of the more interesting findings. If you didn’t already know, we keep track of exactly which email clients your subscribers are using and present that in a nice report for each campaign you send. Knowing which email clients your subscribers might be using can be extremely useful when coding your emails. If you don’t have to worry how your email will look in Lotus Notes 6, you just saved yourself a few hours of frustration.

There is however one limitation on how we can measure which email clients a subscriber is using. Basically, we need your subscriber to have images enabled, or to click a link in your campaign. If they open your email with images disabled, there’s just no way we can access that data. This, of course, means that those email clients that disable images by default (like Gmail, Yahoo, Hotmail and Outlook) will appear to be less popular than those that don’t disable (like Apple Mail and the iPhone). The report still gives you a very good indication, but it’s not perfectly accurate.

What is accurate however, are the trends that we measure in usage over time.

It’s all about the trends

While image blocking can create minor distortions in exactly which email client is the most popular, it’s irrelevant when we measure the change in usage of that particular email client over time. Unless an email client switches their default on image blocking (none did), it’s an extremely accurate way of seeing which clients are being used more, and which are falling out of fashion. Here are the big changes we uncovered in our 2009 number crunching:

Email client Change in usage
iPhone  128.6%
Apple Mail  21.37%
Hotmail  6.7%
Gmail  6%
Thunderbird  3.5%
Outlook 2000 to 2007  9%
Yahoo! Mail  9.8%
MobileMe  11.8%
AOL Webmail  38%

iPhone usage grows almost 130%

While some of our previous claims about the growth of iPhone email client market share were often met with criticism, one thing is certainly clear – iPhone is growing. Fast. Not only did usage more than double in 2009, but the low friction upgrade system built into iTunes has ensured customers upgrade quickly.

iPhone OS 3.0 was the fast growing email client of the year with market share growing to more than 7%. Since its release in June 2009 it now comprises more than 80% of all iPhone usage. At the same time, iPhone 2.0 was the fastest shrinking client and lost more than 3% total market share last year.

Apple Mail up 21%

In reflection of the continued growth in sales of Apple hardware in 2009, Apple Mail usage across version 2, 3 and 4 grew by a total 21% throughout the year. Apple Mail 4 was released with OS X Snow Leopard at the end of August 2009 and was the second fastest growing email client of the year. Latest figures indicate version 4 will soon surpass the usage of version 3. It’s been a dominant year for Apple.

Outlook 2007 growing, but not fast enough

Impressively, use of Outlook 2007 grew by 50% over the course of 2009. However, the total usage of Outlook across all versions (from 1998 through to 2007 inclusive) actually dropped by 9%. While a large number of Outlook users are upgrading to the latest version, it seems a significant percentage are also switching to other email clients.

Yahoo! Mail slips while Hotmail and Gmail gain

On the web-based email client front, Yahoo! Mail is the only major client to see a reduction in market share over 2009, dropping almost 10% last year. Hotmail, on the other hand, grew by 6.7% and Gmail was right behind with total growth of 6%. AOL Web Mail usage dropped a significant 38% and Mobile Me use dropped almost 12% too.

Some closing thoughts

While these observations are interesting from a big picture perspective, you really should look at your own results when making decisions about which email clients to build and test for. One thing’s for sure, mobile email is the fastest growing area of the market today and shows no signs of slowing down. We’ve been doing more research lately on getting the best results for these clients, and we’ll be publishing a few of the more interesting discoveries soon.

How do these industry-wide results stack up against the usage your seeing for your own subscriber lists?

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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