Choosing the right email marketing retina image size helps graphics look sharp on high-density desktop and mobile displays. Mail Designer 365 can create Retina-optimized images for your design and warns you when an image does not have enough resolution for its displayed size.
Retina optimization works best when the source image contains enough pixels for the area where it will appear. If the source is too small, either replace it with a higher-resolution version or reduce its displayed dimensions in the email design.
Understand Retina images for email
A high-density display uses more physical pixels to render the same visual area. A Retina image therefore needs more source detail than an image intended only for a standard-density display. Mail Designer 365 uses the design size and available image resolution to help create a sharper result.
The desktop and mobile switch indicates when Retina support is active. When the option is enabled, Mail Designer 365 automatically prepares Retina-optimized images for the corresponding version of the template.
Watch for the low-resolution icon
Mail Designer 365 checks images added to the mobile version. When an image has insufficient resolution for its current displayed size, a warning icon appears.
Select the affected image and read the warning. It identifies a potential quality problem before you send the email.
Fix an image that is too small
You have two practical options. Replace the source with a higher-resolution image that uses the same composition, or make the existing image smaller inside its image area. Reducing the displayed size means the available pixels cover a smaller area and can produce a sharper result.
Do not enlarge a low-resolution source merely to fill more space. Scaling it up does not create real detail and may make softness or compression artifacts more visible. When replacing an image, preserve the intended crop and check that any important product or brand details remain accurate.
Enable Retina images in Design Options
Choose File > Design Options to review the Retina settings for the current design.
For the desktop version, make sure Create retina images for desktop is selected when you want high-density desktop graphics.
For mobile, enable Create retina images for the mobile version. Review both settings because a campaign may use different image sizes or crops in its desktop and smartphone layouts.
Balance image quality and email size
Use the resolution required for a clear result, but avoid unnecessarily large source files. Oversized images can increase the amount of image data used by the message without improving the visible result. Crop unused areas before adding an image and choose sensible displayed dimensions for the design.
Keep important text as live text rather than placing all copy inside images. This improves readability when images are blocked and avoids depending on image resolution for essential information.
Test Retina images before sending
- Review every warning icon in both desktop and mobile versions.
- Check the design at normal size rather than judging only while zoomed in.
- Send a test email and inspect key images on standard- and high-density displays where available.
- Confirm that images remain sharp without covering text, buttons, or links.
- Verify that alternative text communicates the purpose of meaningful images.
For more image and layout guidance, browse the Mail Designer 365 Knowledge Base.
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