Klaviyo will automatically optimize all emails for mobile viewing. You can also choose to disable all mobile optimizations by navigating to the Styles tab of your email template.
When building a template, you can toggle between desktop and mobile preview.
General Mobile Optimization Options
If you choose to enable mobile optimizations, certain adjustments will be made automatically to optimize your email's appearance when viewed on a mobile device.
Columns, for example, automatically stack column content for mobile viewing. If you would like your columns to be preserved, disable optimizations in the Mobile section of your template's Styles tab.
There are a number of other settings that allow you to make adjustments specifically for mobile viewing.
Stack on Mobile vs. Hide on Mobile
Stretch Image Option
For an image block, you can choose to stretch an image to the full width of the frame when viewed on mobile. You will see this option in the Block Styles tab for any image block. The Stretch Image option will allow you to toggle between Yes (Stretch) and Inherit (Not Stretch).
Email Client Support for Mobile Optimization
Many email apps have varying levels of support for mobile optimizations, the following is taken from a Litmus infographic on responsive email design.
The iPhone Gmail app strips out all mobile optimizations.
If you are concerned about how your email design will render across different email clients and devices, using a third-party email testing tool can help.
We recommend exploring the use of a tool like Litmus, which offers a free trial as well as monthly paid plans. You can also search for free alternatives that allow you to test and preview how your emails will look when viewed by recipients using different email clients and devices.
Determine How Many Subscribers Are Opening on Mobile
In the Advanced Reports tab of a given campaign, you can see a breakdown of how many recipients opened your email on a mobile versus desktop browser. This can give you an indication of how your audience is interacting with your emails.