Last updated: 14 October 2026
Standard testing coverage
To ensure consistent quality and reliable email rendering, Mapp maintains a defined set of email clients, devices, operating systems and display modes for standard Email CMS testing.
A preview shows how an email renders in a specific email client, device and operating system. The previews listed under Tested previews represent our standard testing coverage. Mapp Email CMS blocks and templates are developed and regularly validated against them.
Testing against current environments also ensures our code stays as modern as possible. Supporting outdated email clients often means relying on older coding techniques, so focusing our standard testing on up-to-date clients allows us to use current, well-supported HTML and CSS practices.
The selected previews provide good coverage for general HTML email development and testing. However, this list will be reviewed and updated as devices, email clients and operating systems evolve.
As older technologies become obsolete, fall out of common use or are no longer actively maintained or supported, they will be removed from our standard testing list. Likewise, newer devices, email clients and operating systems will be added as they become relevant to ensure our testing coverage remains current.
What this means for you
Included in standard testing: the email clients, devices, operating systems and display modes listed under Tested previews.
Not included in standard testing: any environment or combination not listed under Tested previews, including older or newer versions and the Excluded previews.
Additional requirements: if your audience requires testing or optimization for an environment outside the Tested previews, please contact your Customer Success Manager.
We are happy to review additional requirements. Depending on the requested scope and effort, additional testing or compatibility adjustments may incur professional services fees. Any applicable costs will be communicated and agreed upon before chargeable work begins.
Note
An environment that is not part of our standard testing is not necessarily incompatible with Email CMS. It simply means that we do not routinely validate or maintain compatibility for that specific environment.
Email rendering may vary between clients, devices, operating systems and software versions. Testing against the listed environments does not guarantee identical rendering in every configuration.
Tested previews
Mobile
Gmail Android (2)
Gmail App Pixel 7, Android 13
Gmail App Pixel 7, Android 13 (Darkmode)
Gmail iOS (2)
Gmail App iPhone 13, iOS 15
Gmail App iPhone 13, iOS 15 (Darkmode)
Outlook iOS (2)
Outlook App iPhone 13, iOS 15
Outlook App iPhone 13, iOS 15 (Darkmode)
The Gmail and Outlook apps render emails the same way regardless of iPhone model, so one device gives representative coverage for these apps.
Apple Mail iOS (14)
iPhone 16, iPhone 16 Pro, iPhone 16 Pro Max, iOS 18 (Light and Darkmode)
iPhone 17, iPhone 17 Pro, iPhone 17 Pro Max, iOS 26 (Light and Darkmode)
iPhone 18 Pro, iOS 27 (Light and Darkmode)
Webmail
Email provider | Chrome | Firefox |
|---|---|---|
AOL | Light + Dark | Light + Dark |
Free.fr | Light + Dark | Light + Dark |
Gmail.com | Light + Dark | Light + Dark |
GMX | Light | Light |
Libero | Light | Light |
Microsoft365.com | Light + Dark | Light + Dark |
Outlook.com | Light + Dark | Light + Dark |
T-Online | Light | Light |
Web.de | Light | Light |
Yahoo | Light + Dark | Light + Dark |
All webmail previews are on Windows 10.
Desktop
Apple Mail (2)
Apple Mail 16, macOS 13
Apple Mail 16, macOS 13 (Darkmode)
Outlook (12)
Outlook preview | Operating system |
|---|---|
Outlook Microsoft 365 | macOS 13 |
Outlook Microsoft 365 (Darkmode) | macOS 13 |
Classic Outlook (Microsoft 365) | Windows 11 |
Classic Outlook (Microsoft 365) (Darkmode) | Windows 11 |
New Outlook for Windows | Windows 11 |
New Outlook for Windows (Darkmode) | Windows 11 |
Outlook 2019 (120 dpi) | Windows 10 |
Outlook 2019 | Windows 10 |
Outlook 2021 | Windows 11 |
Outlook 2021 (Darkmode) | Windows 11 |
Outlook 2024 | Windows 11 |
Outlook 2024 (Darkmode) | Windows 11 |
Excluded previews
The previews below are no longer tested separately, because they are out of date or share rendering behaviour with previews we still test.
Note
Additional testing or optimization for excluded previews can be requested. The additional effort is assessed first and may incur professional services fees. Please contact your Customer Success Manager (CSM) to discuss your requirements.
Mobile (16 excluded)
Gmail Pixel 6, Android 12 (Light and Darkmode)
iPhone 14, iPhone 14 Pro, iPhone 14 Pro Max (Light and Darkmode)
iPhone 15, iPhone 15 Plus, iPhone 15 Pro, iPhone 15 Pro Max (Light and Darkmode)
Older devices and operating systems with largely overlapping rendering behaviour. Newer generations remain selected.
Webmail (16 excluded)
AOL, Free.fr, Gmail.com, Microsoft365.com, Outlook.com and Yahoo: Edge previews
GMX, Libero, T-Online and Web.de: Edge previews
Microsoft Edge and Google Chrome both use the Chromium rendering engine, so their HTML/CSS rendering behaviour is generally very similar. Chrome and Firefox remain selected to provide coverage across different browser engines.
Desktop Outlook (4 excluded)
Office 365 (now Microsoft 365), Windows 10: Light and Darkmode
Outlook 2016, Windows 10
Outlook 2016, Windows 10, 120 DPI
Other retained Outlook previews provide representative coverage across different versions, rendering environments and DPI settings.