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Without doubt, the biggest frustration for us email designers is the huge variety of email clients we need to test our designs in. It’s a monumental challenge that makes building and testing HTML emails far more difficult than designing for the web.

Today, I’m super excited to announce that we’ve officially solved this problem. Yes, you read that right. For every campaign you send, we’ll now provide a clear breakdown of exactly which email clients your subscribers are using. Is anyone really using Lotus Notes? How many subscribers are actually using Outlook 2007? Should I be testing my emails on an iPhone? Up until now that’s been total guesswork. No longer.

Sample email client report

What’s so cool about this?

In a single new report, email has just caught up with the web. It’s easy to look at your web analytics and decide it’s not worth testing in IE6 any more. Now you can be just as informed about which email clients to worry about.

Personally, this report has already been a huge help for our own email newsletters. I never would have guessed that more than 7% of our subscribers open our emails on their iPhone, which has more than doubled since a newsletter I sent last August. If the trend continues it will be more popular than both Gmail and Outlook 2007 for our next issue. Crazy. Likewise, I never would have assumed that AOL, MobileMe and Entourage make up less than 1% of my subscribers combined. They certainly won’t be getting as much attention in the future.

As well as showing which email clients are being used, the report also splits them up by version. This is crucial for email clients like Outlook, where your real concern is Outlook 2007 users (which has poor standards support) as opposed to those using previous versions (which have great standards support). We also list the 8 most popular clients at the top of the report so you can quickly see the versions that need your attention.

Everyone’s different

Sweeping statements about B2B subscribers using Outlook/Lotus Notes and B2C using Hotmail/Yahoo!/Gmail have officially been blown out of the water. The most surprising thing we discovered building this report was just how different the results looked for different senders. Even companies in very similar industries still showed some big differences.

That’s what makes this report so useful. You can completely tailor your design and testing process on a client-by-client basis to guarantee you cover all the important email clients and don’t waste a minute of your time on those that aren’t. It’s a huge time saver.

How do we know what your subscribers are using?

The accuracy of this report is something we’ve been working hard on. We analyzed more than 200 million opens over the last 6 months to ensure we had a consistent way to detect more than 20 of the most popular email clients out there. We’ve also been careful to build this in a way that adapts to the market. We can easily update your reports if a new version of a client is released and we’ll continue to refine our tracking to keep the report as accurate as possible.

There is one small caveat. We can only detect an email client when an image is displayed. If your recipients email client blocks images and they don’t enable them, or doesn’t support images at all (older versions of Blackberry and Windows Mobile for example) they won’t appear in your report.

The best part is, we’ve been capturing your subscribers email clients for the last 6 months, so it’s already available for any campaigns you’ve sent in that time. If you’re a previous MailBuild customer, you can check it out for any campaigns sent since the merger last December.

We’ve got some exciting plans about helping you get the most out of this data in the future, which we can’t wait to share with you. In the mean time, head into your campaign reports and take the guesswork out of your email design.

  • Mark Wyner

    Pure rock and roll. Can it get any better?

  • Erwin Heiser

    Awesomeness :)

  • Luc Pestille

    Impressive, most impressive.

  • Nathan Pitman

    Very impressed by the fact that you have provided us all with these stats for old campaigns too! This really will be a very useful feature.

  • Paul Cripps

    As outstanding as always… cant wait to re-review old campaigns.

  • James

    Great stuff guys!

  • Matt

    This is fantastic. Thanks guys!

  • Damien Buckley

    This is a massively useful introduction – nicely done!

  • Darren

    Fantastic stuff. No surprises (unfortunatly that Outlook 2003, 2007, Express…) top the results. Though Yahoo, Apple Mail are doing well.

  • Elke Bretz

    Very, very useful. This is an excellent report. Thanks!

  • jason

    How good is this! Just when you think Cm can’t get any better you go and add something like this. Fantastic

  • Jonny Vaughan

    That is pretty cool. I love the fact it’s retrospective too.

    I also like that you can click on a segment on the pie chart and it pops out… Serves no purpose but it looks funky ;)

  • Raj

    You guys never stop shining!

  • Armistead Booker

    Smiling from ear to ear… very good news! Interesting to see that in most of my reports, Apple Mail 3 is outranking Apple Mail 2 by leaps and bounds. But excited to explore how these demographics change between different audiences (I smell a sociology book in about five years). Could a sweeping end-of-year report on these trends across Campaign Monitor users be possible?

  • Scott Spaid


  • Rick

    Perfect. I was hoping you would add this. Thanks!

  • Savageman

    Very cool!
    Just a suggestion, you should add the new features on the “features tour” page (some new stuff on the reporting-and-analytics page).

  • Ali


  • Scott Jacques

    Team CM Rocks Again! By far the best email marketing app out there.

  • Alex Dunae

    Hell yeah! I’d been begging various listservs to provide aggregated stats to make Premailer‘s warnings more useful, but this is just over-the-top.

    Nice work.

  • Wayne

    why not just use your web analyics tool for this?

  • Chriz

    Amazing and pretty cool – thanks!

  • Mike Bowzeylo

    Super awesome… because it’s super useful. Another reason to love CM… you guys include features that are cool AND functional, not just eye candy or marketing gimmicks.

    Once again I tip my hat to you fine folks.

  • Tobz

    super awesome alright. I’ve been waiting for this for EVER.

    Just looking at my all clients stats and I’m really happy on how few people are on Outlook 07
    In fact over the course of December one clients OL07 numbers went down quite dramatically.

    Great job guys – keep up the good work.

  • Jayne

    Thanks guys this is brilliant… This may just be the excuse I need to buy an iPhone. I can now see exactly how many people are viewing on a device I just can’t test for at the moment.

  • John

    You guys continue to set the standard!
    Your competitors don’t stand a chance

    : )

  • Ugur Gundogmus

    Last month, we tried another popular email campaign software for one of our clients. I have to say Campaign Monitor is the best. Keep up the good work.

  • Jesh

    Holy cow! Our agency clients are going to flip when they see this! No more building for EVERY email client… It’s bedtime in the States and you send me this exciting news? How am I supposed to sleep?

  • piet

    love you : )

  • Zen Web Solutions

    What a great reporting tool! Now just looking forward to being able to test our emails in Apple Mail and iPhone/iPod Touch within Campaign Monitor, currently doing that manually (which works fine but would be better all in one place!).

  • Julia

    OMG! You guys are awesome! You think of things forwards and backwards. We’re completely covered.

    And yet, I’m equally amazed that ANYONE uses Notes at all! Yet, there they are, listed on our new reports. Bummer.

    Maybe you can come up with some Notes Corrupter that would force everyone to convert to something else? ;-]

  • Prashant

    Great feature, nice work!

  • Natalia

    One more great improvement! Can Campaign Monitor get even better?

  • Ilker Ergen

    You’re great people. Best wishes to you.

  • Alissa

    This.is.awesome. Finding this articel just relived a HUGE amount of stress I have been having with one particular client. Thanks!

  • David Greiner

    A huge thanks to everyone for the amazing reaction, we couldn’t have asked for a better response than that! We won’t be sitting on our hands now either, and have a some great ideas on how you can get the most out of this data. We’ll keep you all in the loop as things come together, but in the mean time we’d love to hear your feedback on any improvements you think we can make.

  • Graham Laker

    Better just got better – really impressed!

  • Patrick Burt

    So, I know my recipients are using Groupwise and some are viewing in html, however most are viewing text. In my reports, I don’t see any opens in groupwise? Does it not detect it? I know for a fact that some opens are in groupwise, I have witnessed it.

    Other than that, this is really awesome.

  • David Greiner

    Patrick, unfortunately not all email clients use any discernible headers that let us track them, which would place them in the “not detectable” numbers. I can certainly pass this on to the team though so we can verify if this is the case or not.

  • Rob Bare


  • Manolo

    Finally a way to convince my clients that not everyone out there is using Outlook! Thx a lot!

  • Fred

    I just died and went to heaven!

  • David

    Awesome. Very usefull indeed!

    Suggestion wise: How about a donut-graph of email clients for each of your subscriber lists (averaged over the life of the list).

    Thanks for making our lives easier.

  • winethex

    you guys are kicking arse. sweet feature. mahalo!!

  • Béate Vervaecke

    That’s a nice feature!
    It looks like Outlook Express (B2C) is sending the same ID as Outlook 2003 (B2B)?
    I also assume Vista Mail is disguised as Outlook Express?

  • Pierre

    nice !

  • Eddie Johnson


    Are there plans to add functionality the the report exports other than the summary?

  • David Greiner

    Not at this stage Eddie, but if it’s something we get lots of requests for it will certainly be considered. it was originally not included because in many cases this information is important for designers, but often not for their clients, which is who the export facility is really built for.

  • Fred Campbell

    Supa Dupa! As usual

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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