What Is Email Testing?
Email Testing lets you see exactly how your email will render across platforms. This helps you catch layout issues early. It also ensures your design looks consistent everywhere.
Email Testing shows how your email appears across:
Mobile devices
Desktop devices
Operating systems
Browsers
Email clients
Light Mode and Dark Mode
What Counts as a Test?
Each email client preview counts as one test.
Example:
You have 10 email clients configured.
You click Email Testing once.
10 previews generate.
10 tests are used.
Each preview:
Is rendered separately
Has its own loading status
Is tracked independently
If you want to know how many tests remain in your contract, contact your Customer Success Manager.
How to Access Email Testing
There are two ways to open Email Testing.
Option 1: From the Actions Menu (Top Right)
Use this method if you want to quickly run previews directly from the builder.
Open your email in the builder.
Click the Actions menu in the top right corner.
Click Email Testing.
Option 2: From Preview Mode (Bottom Right)
Use this method if you want to review your email first.
Open your email in the builder.
Click Preview in the bottom right corner.
Click the Email Testing icon tab (device icon).
Review Your Email Previews
Wait for previews to load.
Click any thumbnail to open a full preview.
Click Refresh Previews
Filter by Device
Filter by Light Mode or Dark Mode
Navigate Between Tests
Select another thumbnail from the right panel.
Click the blue X to exit the email client and return to grid view.
Click the Back to Editor button in the top-left corner to return to the builder.
Role Permissions
You can control who can generate previews. This helps manage test usage.
Allow Non-Admins to Generate Previews
Go to Admin.
Click Roles.
Select the role you want to update.
Enable Can generate email client previews.
Click Save.
Customize Email Clients (Admins Only)
You can control which clients are available for testing.
Add or Remove Email Clients
Go to Admin.
Click Settings.
Scroll to Email Testing.
Click Customize Email Clients.
Click the + icon to add a client.
Click the X to remove a client.
Click Save.
Clients Available
Client | Operating System |
Gmail App Pixel 3 | Android 9 |
Gmail App Pixel 4 | Android 10 |
Gmail App Pixel 4 | Android 10 (Dark Mode) |
Gmail App Pixel 5 | Android 11 |
Gmail App Pixel 5 | Android 11 (Dark Mode) |
Gmail App Pixel 6 | Android 12 |
Gmail App Pixel 6 | Android 12 (Dark Mode) |
Gmail App Pixel 7 | Android 13 |
Gmail App Pixel 7 | Android 13 (Dark Mode) |
iPhone 11 | iOS 15 |
iPhone 11 | iOS 15 (Dark Mode) |
iPhone 12 | iOS 15 |
iPhone 12 | iOS 15 (Dark Mode) |
iPhone 12 Mini | iOS 15 |
iPhone 12 Mini | iOS 15 (Dark Mode) |
iPhone 13 | iOS 15 |
iPhone 13 | iOS 15 (Dark Mode) |
iPhone 13 Mini | iOS 15 |
iPhone 13 Mini | iOS 15 (Dark Mode) |
iPhone 14 | iOS 16 |
iPhone 14 | iOS 16 (Dark Mode) |
iPhone 14 Pro | iOS 16 |
iPhone 14 Pro | iOS 16 (Dark Mode) |
iPhone 14 Pro Max | iOS 16 |
iPhone 14 Pro Max | iOS 16 (Dark Mode) |
iPhone 15 | iOS 17 |
iPhone 15 | iOS 17 (Dark Mode) |
iPhone 15 Plus | iOS 17 |
iPhone 15 Plus | iOS 17 (Dark Mode) |
iPhone 15 Pro | iOS 17 |
iPhone 15 Pro | iOS 17 (Dark Mode) |
iPhone 15 Pro Max | iOS 17 |
iPhone 15 Pro Max | iOS 17 (Dark Mode) |
iPhone 16 | iOS 18 |
iPhone 16 | iOS 18 (Dark Mode) |
iPhone 16 Pro | iOS 18 |
iPhone 16 Pro | iOS 18 (Dark Mode) |
iPhone 16 Pro Max | iOS 18 |
iPhone 16 Pro Max | iOS 18 (Dark Mode) |
Outlook App iPhone 13 | iOS 15 |
Outlook App iPhone 13 | iOS 15 (Dark Mode) |
Outlook App Pixel 6 | Android 12 |
Outlook App Pixel 6 | Android 12 (Dark Mode) |
Apple Mail 16 | macOS 13 |
Apple Mail 16 | macOS 13 (Dark Mode) |
Outlook Microsoft 365 | macOS 13 (Dark Mode) |
Outlook Microsoft 365 | macOS 13 |
Outlook Office 365 | Windows 10 |
Outlook Office 365 | Windows 10 (Dark Mode) |
Outlook 2016 | Windows 10 |
Outlook 2016 (120 dpi) | Windows 10 |
Outlook 2019 | Windows 10 |
Outlook 2019 (120 dpi) | Windows 10 |
Outlook 2021 | Windows 11 |
Outlook 2021 | Windows 11 (Dark Mode) |
Outlook Microsoft 365 | Windows 11 |
Outlook Microsoft 365 | Windows 11 (Dark Mode) |
AOL | Windows 10 Chrome, Edge & Firefox |
AOL | Windows 10 (Dark Mode) Chrome, Edge & Firefox |
Google Workspace | Windows 10 Chrome, Edge & Firefox |
Gmail | Windows 10 Chrome, Edge & Firefox |
Gmail | Windows 10 (Dark Mode) Chrome, Edge & Firefox |
Windows 10 Chrome, Edge & Firefox | |
Windows 10 (Dark Mode) Chrome & Edge | |
Windows 10 Chrome, Edge & Firefox | |
Windows 10 (Dark Mode) Chrome, Edge & Firefox | |
Yahoo | Windows 10 Chrome, Edge & Firefox |
Best Practices for Accurate Previews
Large images can affect preview accuracy.
The preview tool captures screenshots quickly. If an image loads slowly, it may not appear in the preview. The live email may still display correctly.
Image Guidelines
Keep images under 1MB
Export images at 2x the display width
Example: If image displays at 600px, export at 1200px
Keep GIF file sizes smaller
Avoid oversized GIFs in Outlook
These steps improve rendering consistency across clients.
Frequently Asked Questions
Why Don’t Token Placeholder Values Appear in Email Testing?
Email Testing uses the same HTML as Download as HTML. It does not render placeholder tokens from your Marketing Automation Platform (MAP). A Marketing Automation Platform (MAP) is the system that sends your emails and replaces tokens with real data.
To confirm your tokens work:
Export the email.
Preview it inside your MAP.
Confirm tokens populate correctly.
Need more help? Contact support via live chat using the chat bubble in the bottom right corner or email support@knak.com.