If you’re sending marketing emails, transactional updates, or even the occasional company newsletter, you know the pain: your message looks perfect in Gmail, but Outlook mangles it, and who knows what’s happening on that old iPhone your boss insists on using. This guide is for anyone who wants their emails to look right everywhere—and wants to actually get there, not just talk about it. We’ll cut through the fluff and show you how to use Litmus to test email rendering across devices and clients without losing your sanity (or whole afternoons).
Why Email Rendering Is a Headache (and Why Litmus Helps)
Let’s be honest: HTML emails are like websites from 2004, held together with tables and hope. Every email client—Gmail, Apple Mail, Outlook, you name it—has its own quirks. What looks great in one might be unreadable in another.
That’s where Litmus comes in. It lets you preview your email in dozens of real clients and devices, so you can catch ugly surprises before you hit send. But Litmus isn’t magic. If you just upload a file and glance at the previews, you’ll miss the real value. The key is using Litmus methodically—otherwise, you’re just collecting screenshots.
1. Start With a Solid Foundation
Don’t test garbage code. Before you even open Litmus, make sure your email is built on a decent framework or template known to perform well in most clients. If you’re hand-coding, stick to the tried-and-true basics:
- Use tables for layout (yes, really)
- Inline your CSS
- Avoid background images and custom fonts if you need broad compatibility
- Keep your design simple—no full-page hero videos or wild CSS
Pro tip: If you’re using a drag-and-drop builder, check if it outputs clean code. Some “easy” builders create bloated, buggy HTML that trips up even the best testing tools.
2. Set Up Your Litmus Project Properly
Jumping straight into previews is tempting, but save yourself time with these steps:
- Organize by campaign. Create a separate Litmus project or folder for each campaign or regular email type (newsletter, receipts, etc.). It keeps things tidy and repeatable.
- Name versions clearly. If you’re testing multiple drafts, label them with meaningful names—“Q2 Promo v4 mobile tweaks” is better than “final2-really-final.”
- Document changes. Litmus lets you add comments or notes. Use them to track what you changed between tests. This helps when you’re trying to remember why you made that weird padding adjustment last week.
3. Choose the Right Clients and Devices to Test
Litmus offers a laundry list of clients and devices—don’t test everything unless you’re into busywork. Focus on what really matters for your audience:
- Check your analytics. Which email clients and devices do your actual recipients use? Most ESPs (Mailchimp, Klaviyo, etc.) will show you this.
- Cover the big three:
- Apple Mail (on iPhone and Mac)
- Gmail (web and app)
- Outlook (desktop and web)
- Don’t forget Android. Gmail on Android and the Samsung Email app are both worth a look.
- Legacy clients: Only test Outlook 2013 if you know people are still using it.
- Dark mode: It’s not just a fad. Test at least one or two clients in dark mode.
What to skip: Blackberry, Lotus Notes, and other relics. Unless your audience is stuck in 2008, don’t waste your Litmus preview quota.
4. Upload and Run Your First Test
Litmus gives you a few ways to test:
- Upload HTML directly if you’re hand-coding.
- Send a test email to your unique Litmus address from your ESP.
- Integrate with your ESP for smoother workflows (helpful if you’re testing lots of variants).
What works: Sending from your actual ESP is best. Why? Because sometimes ESPs tweak your code in ways you wouldn’t expect (stripping CSS, adding tracking codes, etc.). Testing the “real” output avoids surprises.
5. Review Screenshots Like a Human, Not a Robot
Now for the core of Litmus: the previews.
Go through the screenshots for each client and device you picked. Here’s what to look for:
- Major layout breaks: Columns stacking wrong, buttons disappearing, images off-center.
- Font issues: Some clients ignore web fonts and fall back to Times New Roman (the horror).
- Broken links or missing images: Sometimes images get blocked by default—do you have good alt text?
- Weird spacing: Outlook loves to add random gaps, especially after images or buttons.
- Dark mode disasters: Does your text disappear into the background? Do logos get inverted in weird ways?
Don’t sweat the small stuff: Minor pixel differences are normal. Focus on things that would actually make the email confusing or ugly for the reader.
Pro tip: If you’re troubleshooting a stubborn issue, use Litmus’s “compare mode” to see what changed between versions.
6. Fix Issues Strategically
Not every issue deserves a fix. Here’s how to decide:
- Deal-breakers: Broken layouts, unreadable text, missing calls-to-action—these must be fixed.
- Minor quirks: Slightly different padding or font size in one client? Unless it looks truly bad, let it go.
- Impossible fixes: Some Outlook versions simply won’t support background images or rounded corners. Know when to give up.
When you do fix, change one thing at a time and re-test. Trying to fix five issues in one go usually creates five new problems.
7. Use Litmus Extras (But Don’t Get Distracted)
Litmus offers more than just previews:
- Spam testing: Decent for catching major problems, but don’t obsess. No tool can guarantee inbox placement.
- Accessibility checks: Worth running, especially for big campaigns. At least check for missing image alt text and low-contrast text.
- Analytics: If you need to prove ROI or see engagement by client, Litmus tracking can help. Just be wary of privacy issues—some recipients block tracking pixels.
What to ignore: The “Checklists” feature is fine, but don’t get lost in checkboxes. Real-world testing trumps any automated scorecard.
8. Share Results and Get Feedback
Litmus makes it easy to share test results with teammates or clients—send them a read-only link to the previews. This is way better than sending screenshots in a 10MB PDF.
- Pro tip: Use comments to highlight issues or ask for feedback, so you’re not stuck in endless email threads.
- Keep a record: If you’re part of a team, save your best-performing templates and fixes. Future-you will thank you.
9. Don’t Forget the Real Inbox Test
Here’s the dirty secret: No matter how good Litmus is, nothing beats opening your test email in real clients on real devices. If you can, check the email on your own phone, desktop, and webmail accounts—especially for the top three or four clients.
Why? Sometimes subtle things—like how Gmail clips long messages, or how images download on slow connections—don’t show up in static previews.
10. Iterate, Don’t Overthink
You’ll never get every email looking 100% identical everywhere. Don’t waste hours chasing pixel-perfection in Outlook 2016 just to please a tiny slice of users. Focus on clarity, readability, and core functionality. If your main message comes through and your CTA works, you’re winning.
The Bottom Line
Litmus is a powerful tool, but it won’t make your emails bulletproof by itself. Use it to spot big problems, not to chase perfection. Keep your tests focused, your code simple, and your process repeatable. When in doubt, check what actually matters to your audience—and always give it a real-world inbox test before you go live. Simple beats clever, every time.