Built-in dark mode in Stripo: How Stripo helps you test emails faster

Do you use dark mode on your computer or smartphone? Maybe you switch to it in the evening to give your eyes a break? Research shows that more than 82.7% of people use dark mode on at least one device, so optimizing emails for dark mode has become essential for anyone creating marketing emails.

That’s why Stripo now includes built-in dark mode preview directly in the editor. You can switch between light and dark modes while designing an email and quickly check contrast, readability, and image behavior before moving on to full testing.

Important to note:  Email clients handle dark mode differently, so dark mode preview tools, including Stripo, show an approximate result. The preview helps you catch potential issues early during design, before full testing.

Why is it important to check how your emails will be displayed in dark mode directly in the editor?

Dark mode inverting colors for copy, backgrounds, and buttons can result in the following conflicts:

1. To ensure proper color contrast for accessibility and readability. Color contrast is important in email marketing overall, but it’s also a requirement for email accessibility. Strong color contrast helps your email stay easy to read on any device and in any lighting situation.

Your design may have a pretty good contrast in light mode, but it may become less readable or disappear entirely in dark mode. Therefore, it is worth being aware of this in advance so that you can adjust your design and prevent key elements from becoming indistinguishable or disappearing entirely.

Low color contrast

(Source: Stripo email template)

High color contrast

2. To check images and logos for visual integrity in Dark Mode. If you’ve poorly cropped images and “smoothed over” everything with a background, all these flaws will become very noticeable in dark mode.

Dark mode support in Stripo

Before, the process was repetitive. You designed an email, sent test emails to see how it rendered in dark mode in real inboxes or used tools like Email on Acid, fixed issues, and tested again. Spotting rendering problems across email clients often required several rounds of testing, which could take as much time as designing the email itself.

With dark mode preview in the editor, you can catch most contrast, readability, and image issues earlier in the design process. As noted above, the preview is approximate:

• if you see contrast or readability issues in dark mode in Stripo, similar problems are very likely to appear in at least some email clients; 
• if everything looks readable and balanced in the editor, your email is generally safe for dark mode, though exact rendering may vary.

Final testing in real inboxes or with tools like Email on Acid is still essential, but it now happens after early checks, not before.

How to switch between dark and light modes in the email editing area during the design process

So, you go to the email editing area. In the screenshot, you see how the email template is displayed in the usual light mode.

In the upper right corner of the top panel, next to the button for switching between desktop view and mobile view, there is an expand button. When we click on it, a drop-down menu appears. The last item in the drop-down menu is theme emulation. This is our switcher between dark and light modes.

If you click the button and select a different symbol, the editor will switch to dark mode, and you will be able to see what your email looks like in a dark theme.

How to check dark mode in the preview mode

Now, if you need to see how your email will look in preview mode, simply click the “Preview” button on the top panel of the editor.

We’ve switched to preview mode. The toggle for switching between light and dark modes is located at the top center. In preview mode, you can see your email in both desktop and mobile views at the same time.

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Testing dark mode: What your subscribers see

Testing is key to ensuring that your ideas meet the needs of your customers. Since different email clients handle dark mode in different ways, this affects how your emails are displayed.

That’s why we decided to test how emails appear in dark mode in the Stripo editor compared to the dark mode in the most common email clients.

Some email clients don’t actually support dark mode. Their interface may appear dark, but the email itself remains on a light background. These include Yahoo! Mail, AOL Mail, Apple Mail, and Gmail on desktop/web. 

According to the Litmus Email Client Market Share Report, the three most popular email clients are:

• Gmail mobile app (Android);
• Gmail mobile app (iOS);
• Outlook Office 365.

For testing, we selected four templates: one with a light theme, one with a dark theme, one neutral, and an email with interactive content.

*We tested the emails, focusing on background and text contrast. We used the tool Accessible Color. The minimum required contrast ratio is 4.5.

Email 1: Designed with light colors

Across the email clients we tested, dark mode modified colors. In Gmail, colors were partially changed, while in Outlook Office 365 on Windows 10, they were dimmed rather than inverted.

In Gmail and Outlook, real email clients showed lower color contrast than the Stripo editor. This should be considered during the design and testing process. While iOS showed a significantly higher color contrast.

This tool mimics the visual output of the following email clients:

• Outlook 2021 Windows 11;
• Outlook Office 365 Windows 10;
• Outlook Microsoft 365 Windows 11.

Please check the link to see the results of the tests we conducted with Email on Acid.

Email 2: Designed in neutral colors, neither dark nor light 

In Stripo, the background appeared almost black or dark gray, while most email clients showed it as dark green or brown-green.

The color contrast in the Stripo editor was close to what real email clients displayed or even lower, so you can trust Stripo for contrast checks.

This tool mimics the visual output of the following email clients:

• Yahoo on Windows 10 (Edge and Firefox).

Please check the link to see the results of the tests we conducted with Email on Acid.

Email 3: Designed with dark colors

Across the tested email clients, dark mode changed colors and contrast in different ways compared to the Stripo editor. On Android, Gmail shifted the background from black to dark gray, lowering the contrast of the text. On iOS, Gmail fully inverted colors, which kept text readable but caused a white logo to disappear on a white background. In Outlook on Windows, colors were selectively adjusted, reducing visual depth.

This tool mimics the visual output of the following email clients: 

For most major email clients, the dark mode preview produced very similar results, as dark tones are usually preserved.

The exceptions were:

• Outlook 2021 Windows 11;
• Outlook Office 365 Windows 10;
• Outlook Microsoft 365 Windows 11.

Please check the link to see the results of the tests we conducted with Email on Acid.

Email 4: With interactive content

To analyze this email, we focused on the interactive part. In most email clients, the text contrast was higher than what the Stripo editor showed. This means that if your email passes the color contrast check during design, the contrast will usually be even better in real inboxes.

The product rating colors stayed the same across all email clients, except Gmail, where bright green appeared as a lighter green.

This tool mimics the visual output of the following email clients:

• Outlook Office 365 Windows 10;
• Outlook 2021 Windows 11;
• Yahoo, Windows 10.

Please check the link to see the results of the tests we conducted with Email on Acid.

Our tests showed that dark mode rendering does vary between the Stripo editor and real email clients, but the preview gives you a very close picture of what will happen in the wild. When the editor highlights a contrast or image issue, that same problem is very likely to appear in real email clients too. And if your email looks balanced and readable in the editor’s dark mode preview, it’s much more likely to render well across devices — even though exact colors and details can still differ. As always, final testing on real inboxes with tools like Email on Acid remains essential, but now you can catch most issues much earlier in the design process.

Wrapping up

Dark mode has become an important part of email marketing, which makes it essential to check whether emails remain readable and visually balanced when dark mode is applied.

Stripo lets you switch between light and dark modes directly in the editor during the design process, helping you spot potential dark mode issues such as contrast, readability, or image behavior early on. The results shown in the editor are indicative rather than exact, as email clients apply dark mode differently and final rendering may vary. By identifying risk areas early, you can improve the overall email experience before moving on to full testing.

Clear and readable emails are easier for subscribers to interact with and support long-term loyalty.