Brand & Marketing
      Back to home
      1. Help Center
      2. Internal
      3. Brand & Marketing

      What email clients do we support?

      Why won't every email appear the same for every client, and which ones do we build and test for? Why don't we support Outlook 2016?

      It's technically impossible to code an email so that it appears exactly the same across all email clients (ie Gmail, Outlook, etc), devices, and operating systems.

      HTML emails don’t render the same for everyone because of several factors, including:

      1. Email Client Differences – Gmail, Outlook, Apple Mail, and others have different rendering engines, meaning they interpret HTML and CSS differently.
      2. CSS Support – Some clients strip out or limit support for certain CSS properties (e.g., Outlook ignores background images).
      3. Dark Mode & User Preferences – Email clients can apply their own themes, changing text and background colours.
      4. Device & Screen Size – Emails may appear differently on desktop vs. mobile, and responsiveness isn’t always consistent.
      5. Security & Spam Filters – Some email clients block external images, custom fonts, or scripts for security reasons.

      We test and optimise our email templates to perform all the most popular modern web browsers, operating systems, devices and email clients.

      These are:

      • Gmail (Chrome)
      • Outlook (Android 11.0)
      • Outlook.com (Chrome)
      • Gmail App (iOS 14.2)
      • Gmail App (Android 11.0)
      • Office 365 (Chrome)
      • iPad Pro (10.5 inch) (iOS 13.1)

      Email template support for dark mode or Outlook 16 will not be included, except by specific request, and will require additional scope. 

       

      Why don't we support Outlook 2016?

      1. Declining Market Share:
      As of March 2025, Outlook clients make up around 7.7% of all email opens. Of this, Outlook 2016 usage is a fraction, as most users have moved to newer versions or mobile apps. Optimising for a small and shrinking segment often doesn’t justify the development time.
      Source: Litmus Email Client Market Share

      2. Rendering Issues Unique to Outlook 2016:
      Outlook 2016 uses Microsoft Word’s rendering engine, which leads to significant display inconsistencies:

      • Poor support for modern CSS (e.g. background images, flexbox)

      • No support for animated GIFs beyond the first frame

      • Frequent layout bugs like broken padding, incorrect alignment, and random white lines

      Fixing for these often means using dated coding techniques, which can break layouts on other clients (like Gmail, Apple Mail, or mobile devices).
      Source: Email on Acid – Outlook 2016 Coding Guide

      3. End of Life in October 2025:
      Microsoft has confirmed Outlook 2016 will no longer be supported or updated from 14 October 2025.
      Source: Microsoft Outlook 2016 Lifecycle

      For these reasons, I'd recommend testing emails on newer Outlook versions, but wouldn't prioritise recoding or redesigning emails based on tests for Outlook 2016.