Outlook.com Breaks into Email Client Top Ten at #7

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While market share stats have mostly held steady over the past few months, there were some exciting changes in April.

Not surprisingly, iPhone, Outlook, and iPad continue to top the charts; however, we’ve seen some major changes in the bottom half of the top ten:

  • Yahoo! Mail moved from #7 to #6
  • Yahoo! Mail Classic fell off the bottom of the list
  • Windows Mail is now in the #10 spot

The biggest change was the sudden appearance of Outlook.com in the top ten. In July last year, Microsoft announced that Outlook.com would eventually replace Hotmail. While Hotmail users were encouraged to try Outlook.com, we didn’t see a lot of change until last month, when we noticed the two providers swapping out share.



With Outlook.com now firmly placed in the top ten, it’s important to watch out for some rendering quirks with this client:

  • No support for CSS background images
  • No support for CSS floats
  • No support for the margin property
  • Image blocking
  • No support for ALT text
  • Irritating defaults for standard header tags

The good news is that Outlook.com email testing is included on all Litmus subscriptions.


There has been little change in desktop, webmail and mobile opens:


A small increase in desktop opens was accompanied by decreases in mobile and webmail opens. Desktop opens now represent 34% of total opens, while mobile remains head of the line at 42%. For the first time, webmail opens dropped below 25%.

The trends clearly show desktop and mobile email clients favored over webmail clients. While consumers may continue to use free webmail services such as Gmail and Yahoo!, there’s an indication that they may utilizing IMAP services for these accounts to read email on smartphones and desktop email clients like Outlook or Apple Mail.