The Ultimate Guide to CSS
A complete breakdown of the CSS support for the most popular mobile, web and desktop email clients on the planet.
Try it for freeOutlook.com and the Outlook iOS app added support for CSS background images and some related properties, as well as certain Flexbox and Grid properties.
Also added iOS 11 Mail to the guide, with no noticeable differences from iOS 10.
Microsoft updated the Outlook apps for iOS and Android with more consistent CSS support, including media queries.
A complete rewrite and redesign of the guide, testing 278 different CSS properties and features across 35 email clients.
To accommodate the huge increase in content, we’ve added search functionality and the ability to link directly to individual the email clients and properties for easy sharing.
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Removed support for various selector options (E) in Gmail and added support for direction, vertical-align and list-style-type in Outlook ’07/’10/’13.
Added support for @font-face, @media and HTML 5 media tags in email clients, as well as email-relevant CSS properties. We re-tested all webmail clients and the latest versions of existing clients.
Outlook.com no longer supports the margin CSS property, including margin-top, margin-right, margin-bottom and margin-left. float support has also been dropped.
Added Outlook 2013 Preview. CSS test results are identical to Outlook 2007 and 2010.
See blog post for details.
background-image is now supported in Gmail.
Added email client results for max-width and min-width.
See blog post for details.
Updated guide to CSS in email released.
See blog post for details.
Updated to reflect margin support in Outlook.com.
Updated the guide with the results of our CSS3 email client tests. 21 new properties were added, with varying levels of support observed across the popular email clients. Notably, Webkit clients were big winners, including Apple Mail, iPhone Mail and soon, the iPad. At this stage, CSS3 is recommended for decorative purposes in email (such as adding text-shadow), due to poor support for layout and box-model properties.
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Added test results for the just launched MySpace Mail.
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A complete rewrite of the guide that included 7 new mobile email clients and a focus on the most popular email clients. The web-based version of the guide now features the 10 most popular email clients, while the PDF guide includes all 23 email clients tested.
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Replaced .Mac results with MobileMe.
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We increased the number of clients we tested, 21 in total now. Gmail and Outlook 2007 continue to be our primary focus since CSS support continues to be limited.
Positive signs from Microsoft though, Entourage 2008 was released with significantly better CSS support.
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Outlook 2007 was released with less CSS support than Outlook 2003. A major step back for HTML email design.
New Yahoo! mail was released with better support for CSS, a positive sign to say the least! Windows Live Mail replaced Hotmail and mixed some CSS support in the process.
Read the report
This was our original test. We added Windows Live Mail for the first time and ran through tests on Outlook 2003, AOL 9, Lotus Notes and Eudora.
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