Unlike the web, email HTML has no common standard, and as a result rendering of your email campaigns can vary across different email clients (Our article Will there ever be an HTML Email Standard? has much more background on the challenges around email code).

When we build templates for Taxi users, including the suite of templates included in all Taxi accounts, our approach is to provide the best experience for a given user and their email client, rather than the same experience for all. Therefore in some email clients, the design, layout and formatting of an email campaign may slightly vary.

Our key challenges are:

  • Outlook 2007, 2010, 2013, 2015 have poor support HTML, including less control over background images and no support for animated GIFs.
  • Gmail has limited support for some advanced formatting.
  • Gmail App for Android & iPhone do not support full responsive design. As a result, we use the Hybrid Approach to add some mobile support, but this is not the full mobile experience you might find in apps like the iPhone Mail app.

Supported clients

We have based our list of supported email clients on those available for Litmus testing. We recommend running Litmus Analytics or similar to determine the split of email clients across your audience. 

Mobile Email Clients

These email clients have full responsive support, including the ability to change images for mobile, control over text and design formatting and full control over how content is stacked. 

  • Android 4.4
  • iPhone 5s 
  • iPhone 5s 
  • iPhone 6
  • iPhone 6 Plus 
  • iPhone 6s
  • iPhone 6s Plus 

Non-Responsive Mobile Email Clients

  • Gmail App

The Gmail App for Android does not support media queries, and therefore we cannot provide the full responsive experience for these users. We have built the Taxi templates using the Hybrid Approach, which provides an optimised version of the "desktop" experience for these users. In Gmail App we can stack columns, and re-flow content to fit the smaller screen. There is, however, no support for changing images on mobile, hiding design elements or changing text formatting. 

The Inbox by Gmail app, and later versions of the native Android email app typically behave in the same way as the Gmail App.

The Gmail App for iPhone can behave differently to the Android app but largely has the same issues, and full responsive support is still not available.


Due to their increased screen size, tablets typically show the full width of the email. Where possible, we still optimise support for touch screens, to provide a better experience for tablet users.

  • iPad 
  • iPad Mini

Desktop Email Clients

These email clients are fully supported by our templates.

  • Thunderbird 38
  • Apple Mail 8 
  • Apple Mail 9
  • Outlook 2011 (Mac)
  • Outlook 2016 (Mac)

Outlook 2007, 10, 13 and 15 use the Word engine to render HTML and therefore provide a different experience for users. Whilst we have ensured this is as optimal as possible, including increasing support for background images, there are some challenges: 

  • Animated GIFs are not supported and only show the first frame. 
  • A 20px margin is also displayed around the entire email layout. 
  • There is limited control over the position, tiling and size of background images in these email clients. 
  • When Outlook is viewed on a high resolution screen, text and images can be displayed larger. 

The affected email clients include:

  • Outlook 2007
  • Outlook 2010 
  • Outlook 2013
  • Outlook 2013 120 DPI
  • Outlook 2015 

We are working with industry bodies to help Microsoft improve these email clients.

Webmail Email Clients

These email clients are fully supported by our templates. 

All webmail clients are tested in Internet Explorer, Firefox and Chrome. 

  • AOL Mail 
  • Gmail
  • Inbox by Gmail
  • GMX.de
  • Google Apps
  • Office 365
  • Outlook.com
  • Web.de
  • Yahoo! Mail

Non-Supported Email Clients

Whilst these email clients are available via Litmus testing, we do not support them. 

  • Outlook 2000 
  • Outlook 2002 
  • Outlook 2003
  • Lotus Notes 7
  • Lotus Notes 8 
  • Lotus Notes 8.5 
  • IBM Notes 9

Outlook 2000-3 do not have significant challenges, but are also more than 10 years old and see very little usage.

Lotus Notes 7 has significant challenges rendering HTML, and we cannot provide adequate support for this email client without significantly restricting the experience for all other users. Like older versions of Outlook, Lotus 7 sees very little usage.

Lotus/IBM Notes 8-9 have better support for HTML email and an adequate-to-good experience is provided for these users. However their low usage levels, even for our B2B clients, mean we do not focus on them.

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