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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.

  • Joseph

    The Gmail app on my Android phone blocks images. So not all Android users are getting images by default.

  • Leigh

    That’s incredible, cannot believe the share Apple has with iOS devices, even compared to Android. Webkit on iOS devices rule!

  • Jarrod

    I’m hoping to implement a mobile design later this month, or early July which is based on no data at all – only industry statistics. If even a fraction of the above is true for our customer base, that can mean thousands of people are viewing our email in their mobile when it is not optimised for it.

    Great piece David.

    @Joesph That’s what was said in the article. I’m the same, images are blocked by default by the Gmail app (as it is with the web client).

  • Allan White

    Great article, will be sharing with my team. I just finished creating my first email with CM, which I adapted from your mobile-savvy template based on the Worldview article.

    I’ve noticed a lot of little gotchas and crafty points (Yahoo email issues, use of cm_dontconvertlink, etc.) since then; consider pulling all that together in an updated best-practices template. Use of the media queries is absolutely the way to go, glad to see you using it. Thanks for pushing the state of the art!

  • Michael Bramwell

    “All iOS devices, along with Android and Palm WebOS automatically render images in HTML email.”

    Not true the Gmail app on Android blocks images by default which may help explain that pie chart.

  • David Greiner

    That’s a good call Michael (and Joseph), I was referring to the default email clients on those devices, but given just how popular the Gmail app would be on Android, it would result in a slightly lower overall count for Android. I’ll look into a way that we might be able to split the general Android email client and the Gmail app into a separate report in the future.

  • Ian Pollard

    BlackBerrys have supported HTML emails since OS 4.5 (6 is the latest OS, 5 is the most common). It’s worth noting that BlackBerry users pay a subscription for BlackBerry Internet Services for their email, BlackBerry Messenger, etc; this does not include image downloads, which they would pay for separately out of their data plan. Hence many, many BlackBerry users read emails with images off. BlackBerry renders are always massively under reported.

  • J

    We like sending plain text for mobile. No line breaks except of course for paragraphs. Looks great — like a regular email message.

  • Ben

    Really interesting stats, thanks. I think mobile growth will be good for developers as you’d hope that browser-based emails (whether mobile or not) will become more consistent, and it also means most users will have HTML/CSS compatibility.

  • David Greiner

    @Ian, I didn’t know that excluded image downloads for BlackBerry devices, thanks for clearing that up.

    @Ben, while we’ve still got a long way to go before worrying about some of the desktop clients with poor CSS support (especially Outlook 2007/2010), it’s definitely a great thing that mobile clients are headed in the right direction.

  • Jop Berkhout

    Wow, I can hardly believe it’s going this fast. From 4 to 20% is an incredible increase indeed! I’m optimising for mobile from now on by using more liquid widths.

  • Locked-N-Loaded

    All the more reason to make sure you use ALT tags for your images.

  • Pete

    You have to remember that iOS devices have a “show images” and “do not show images” setting for all email. However, other devices it is up to the user to display the images per email. I imagine this is a major factor in the skew (especially considering Androids growth recently).

  • Stuart

    Why can’t email for mobile be recreated from scratch with enforced standards so we don’t have any platform compatibility/display issues?

  • Paul Egan

    David, I normally open my email on my iphone with gmail web client. So is that counted as a iOS open or something else?

  • David Greiner

    @Paul, that would add a vote for Gmail in that case, not for iOS.

  • Josh Clark

    Yep, the Gmail factor is almost certainly giving you VERY undercounted Android stats. Which also means you’re getting very undercounted mobile stats overall. So the growth in mobile email is probably even bigger than what you’re estimating here. Amazing. Thanks for sharing this.

  • Graham Mallinson

    Very useful – thank you – and a question for David – I had been thinking about where the web emails were being opened before Paul’s question. Is there any way you can get to the next level David and split the web mail by desktop device and mobile? If for example 80% use a desktop to access the web wouldn’t that skew these overal stats considerably? That question aside – it’s a very powerful article David, thanks again.

  • David Greiner

    @Josh, it’s really hard to say just how undercounted these are, as there’s really no way to accurately measure the ratio of users that do or do not enable images. Glad you found the research useful.

    @Graham, that’s something we’re definitely looking into, but having said that, it’s very likely that the majority of those using web-based email providers like Hotmail and Gmail either check that using the web-based version on their desktop, or use a default email client on their mobile device using POP or IMAP.

    The Gmail app on Android is the only popular exception to this, so it isn’t likely to skew the numbers much. But of course, there’s only one way to find out ;) Thanks for the suggestion.

  • Daniel Mee

    Is there a way to check if the same email is first viewed on a mobile but then on a desktop? That insight would tell me if my campaign had relevance (or at least had ‘desktop’ relevance). I know some emails I read on mobile but then delete on my mobile. Others I read but want to follow that up later on my laptop – tracking my “two bites of the cherry” across two different platforms would be insightful….

  • Phil

    I find it hard to believe your stats because I see so many people around me every day with BlackBerry and Android phones as well as iPhones, and they are all constantly reading their emails. I think that if “technical particularities” of each device skew statistics so much as to wipe large chunks of readership, then they are not really worth having because it does not give us a real picture of who reads our emails.

  • Tony

    hey David

    Great work by the way. question – when it comes to mobile – having image buttons to lets say “book a package” vs a text link – which one is better – considering – some email clients lioke outlook will not display images unless the user opts in….i guess this is the image vs html text dilema.

  • Sherri

    In the pie chart “Breaking down the mobile market” where does Blackberry fit in? I see iPhone, iPad, Android, etc, but where is the Blackberry market?

  • WebMatros

    Would be interesting to see the rise of Facebooks messaging service on this graph as well, comparing it to email.

  • Goran Peuc

    I have one serious question regarding the stats above and email users see.

    What I believe is happening is users checking their email in the morning while still in bed or during breakfast on their iOS devices (mostly) through IMAP but then again getting those emails through POP once they get to work. I really have no idea how exactly your tracking works, does it track only first download, or all downloads. However I am sure that people see one email multiple times on multiple platforms. Me and all of my coworkers in team follow this use pattern – open mail at home on iPad, maybe answer something quickly, but then get to work and download all of those emails again in Outlook.

    So, could you elaborate on this data collection – do you collect email data on first or all openings of email? Do you take into account that one email could be opened multiple times across the devices (iPad at home, and then iPhone on commute and then Outlook/Mail at work)?

  • Pete Austin @MarketingXD

    I’ve done my best to correct the math, allowing for the “overcounting” issue identified in previous comments. This changes the headline conclusion to the following:

    “Mobile email clients like the iPhone, iPad and Android have grown from 1% (not 4%) of the market to almost 4% (not 20%) in just two years.


    I would be fascinated to see a report based on click-throughs, or outcomes, as these would not be vulnerable to overcounting in the same way as opens.

  • David Greiner

    @Pete, thanks so much for putting so much thought into this. One important point that you seem to have overlooked here is that we only count one vote for each email client when a subscriber opens a specific campaign. So, even if they open the email 30 times, that particular email client only gets counted once.

    Likewise, if they open the email on 3 different clients all multiple times, we’ll only add one count for each of the three clients too. We’re trying to see which email clients people are using, not how often they are using them. You might consider updating your post to reflect this.

    We’re also considering focusing on link clicks for future emails, and will be running some tests in the coming weeks too gauge how accurate that will be.

    So, in summary mobile usage across those 3 billion + emails was in fact 1 in every 5. As pointed out by other commenters above, image blocking in Gmail for Android and BlackBerry means this may even be underreported, and could be even higher.

    If you have any other thoughts on this, I’d love to hear them.

  • loren paul wiener

    A summary or conclusion would have been useful. This is all interesting but with RIM and Symbian having a combination of 46% of the market (Gartner, 2010 Q4 and Canaylis, Q4 2010), Microsoft with 80% of desktop and Apple with 17.5%, I see nothing here that makes any sense in your numbers. Are you basing your understanding of the mobile market based on your newsletter viewers?
    Australia only, or what, you stats pages do not seem clear on this.
    If your point is that Apple iOS is driving email views, ok. The story to me putting on a global product manager hat, would seem to be you need to attract more Android and Windows Customers, as you are doing the right thing to attract iOS customers.
    Well done.

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