In email marketing, the line between a seamless campaign and a chaotic one often comes down to how well you test. Sending a quick test email to yourself no longer cuts it because emails render differently across clients, and even small inconsistencies can break a layout. That’s why professional teams turn to tools like Litmus and Email on Acid, pairing them with automation to make testing faster, smarter, and more reliable.
As part of a refined email QA process, teams benefit from structured checks that prevent issues before they escalate.
At Email Mavlers, our design and development team swears by these two tools.
But owning them isn’t the real advantage—it’s about building a structured workflow where they seamlessly fit and perform to your specific needs.
In this guide, we’ll show how that workflow looks in real-world projects. Let’s begin!
Why Litmus and Email on Acid Are So Useful
Both Litmus and Email on Acid are built to help you see exactly how your email appears across multiple clients and devices.
Litmus Email Testing
- Instant Previews: Preview your email in over 100 clients (Outlook, Gmail, Yahoo, Apple Mail, etc.)—no manual test emails required.
- Code Checks: Highlights unsupported HTML/CSS or layout breaks.
- Spam Testing: Checks whether your subject line or content might trigger spam filters.
- Email Analytics: Tracks engagement and shows where users click after the campaign goes out.
Email on Acid Testing
- Previews + QA Checklist: Provides rendering previews plus a built-in checklist for step-by-step team reviews, forming the foundation of a sound email QA checklist.
- Link & Image Validation: Automatically detects broken links, missing images, or unoptimized files.
- Accessibility Checks: Reviews color contrast, alt text, and other accessibility details.
- Campaign Precheck: Runs final tests before sending to ensure every image, link, and tracking pixel works.
Both tools test emails in real email clients. So what you see in their reports is exactly what your subscribers will see in their inboxes.
The Email on Acid Testing Method
When using Email on Acid, send test emails directly to their provided address rather than forwarding.
Clients drastically reformat messages when forwarded. Your email client rewrites the entire HTML structure, and recipients (or testing services) receive a mixed-up version that doesn’t reflect your original code. However, there’s a strategic exception to this rule.
Once you’ve mastered inline styles and want to understand email resilience, intentionally forward your test to Email on Acid. This reveals exactly what happens when subscribers forward your campaigns to friends or colleagues—a real-world scenario that often produces broken layouts. Testing forwarded versions across multiple clients shows you how resilient your email truly is and whether forwarded messages remain readable.
Side-by-Side Comparison Power
Testing platforms show thumbnail previews across dozens of clients simultaneously, letting you spot problems at a glance:
- Text rendering quality across iOS versions
- Image scaling behavior on different screen sizes
- Spacing and alignment consistency
- Font fallback performance (verifying Verdana appears instead of Roboto in Gmail)
This bird’s-eye view is impossible to achieve through manual testing—you’d need physical access to dozens of devices and email configurations.
With tools that streamline email HTML testing, teams catch inconsistencies earlier in the pipeline.
Email Template Testing Workflow
Let’s kick off with our 5-step email template testing workflow.
1. From Client to Testing
The process usually begins once your team finishes building the HTML email template. At this stage, the client wants to make sure that:
- The email matches the approved design.
- It looks perfect across all inboxes and devices.
Before scheduling the campaign, always run the template through a pre-send testing platform like Litmus or Email on Acid. This step helps you catch layout or rendering issues early.
Critical reality check: Without professional testing services, you’re essentially flying blind. What renders perfectly in your email client may break catastrophically elsewhere.
Email clients handle HTML and CSS in wildly different ways—Outlook doubles line heights, Gmail overrides fonts with Roboto, and mobile clients add unexpected wrappers that create awkward spacing. You simply cannot know how your email truly performs until you test it across the actual ecosystem your subscribers use.
2. Automating the Testing Process
Testing one or two emails manually is fine. But when you’re managing multiple campaigns a week, automation becomes essential.
Here’s how automation helps streamline day-to-day QA in email production:
Integrations for Litmus Email Testing
You can connect Litmus directly to ESPs like Marketo, HubSpot, Salesforce Marketing Cloud, or Mailchimp.
Whenever someone creates or saves an email, Litmus automatically:
- Runs tests
- Generates previews
- Attaches results directly inside the platform
QA starts automatically, no manual uploads or test triggers needed. This is where automation for email testing becomes a force multiplier.
Email on Acid Automation
Email on Acid offers smart integrations and APIs too. For example, in Marketing Cloud or Pardot, it can trigger tests whenever a new email version is saved or approved.
It automatically checks for spam issues, broken links, HTML errors, and renders.
Continuous Testing Pipelines
Advanced teams connect Litmus or Email on Acid with CI/CD tools such as GitHub Actions or Jenkins. Each time a developer updates email code, the system runs automated tests.
This ensures no broken code ever slips into production. It also reduces manual dependencies and enhances your email QA process with repeatable steps.
Testing Frequency Consideration: When working with platforms such as Marketing Cloud, understand that template changes can sometimes cause content blocks to double up unexpectedly when applying updates to existing messages. While this doesn’t happen every time, it occurs randomly enough that automated testing should verify content integrity after template updates—not just rendering quality.
3. Dynamic Content Testing
Modern email marketing increasingly relies on dynamic, personalized content.
Therefore, your testing workflow must account for this complexity:
Interest Tracking and Real-Time Updates: Tools like Litmus Personalize Pro enable dynamic content that updates based on subscriber behavior. For example, “hot offer” badges can automatically appear when click-through rates exceed thresholds—no manual tagging required.
Test these dynamic elements by:
- Verifying threshold triggers work correctly
- Confirming content updates reflect in cached vs. fresh opens
- Checking that personalization tokens pull correct data
- Ensuring fallback content displays when personalization data is missing
Image Carousel Testing Animated image carousels showcase multiple products or offers in one space, but require specific testing:
- Animation smoothness across clients (some email clients strip animations entirely)
- Frame timing and transition effects
- Mobile rendering (does the carousel remain functional on smaller screens?)
- Fallback images for clients that don’t support animation
Countdown Timer Validation Time-sensitive offers benefit from countdown timers, but these require careful testing:
- Verify timers display correctly across time zones
- Check that expired timers show appropriate fallback content
- Test timer visibility in dark mode
- Confirm mobile rendering doesn’t break timer formatting
4. Testing for Accessibility
Accessibility testing deserves special attention in your workflow. Beyond Email on Acid’s built-in accessibility checks:
Screen reader testing is non-negotiable. Always test emails with actual screen readers. What seems fine visually may create terrible experiences for visually impaired subscribers:
- Alt text verification: Check that alt text works as intended and provides meaningful context/
- Decorative image handling: Use aria-hidden=”true” on decorative images to prevent screen readers from announcing them or reading random file names/numbers.
- Text-in-images problem: When text appears in images (common with “popping out” design elements), it becomes unreadable on mobile when images scale down. Either convert to live text or create separate mobile versions with stacked layouts for readability.
The blank alt text strategy: For decorative images that don’t convey essential information, blank alt text (alt=””) prevents redundant announcements. However, always pair it with aria-hidden=”true” to ensure screen readers don’t attempt to interpret the image filename or generate random announcements.
The Final Pre-send Checklist
Before giving the green light to an email campaign, make sure every item on this checklist is covered. A structured email QA checklist helps ensure nothing is overlooked:
- Cross-client rendering: Confirm consistency across desktop, webmail, and mobile clients.
- DPI scaling: Verify proper rendering for Windows users with 120 DPI (high-resolution) settings enabled.
- Image optimization: Ensure inline images are optimized and capped at 180–200px in width to prevent layout distortion.
- Font validation: Check that custom fonts render correctly and aren’t replaced by system defaults like Roboto (Gmail) or Arial (other clients).
- Dark mode review: Evaluate how the design appears in dark mode—control is limited, but all elements should remain legible and on-brand.
- Forwarding resilience: Test by forwarding to Email on Acid to assess how layouts hold up when subscribers share emails.
- Accessibility assurance: Complete screen reader testing, confirming meaningful alt text and accurate aria attributes.
- Dynamic content validation: Test all personalization tokens, interest trackers, and conditional logic using sample data.
- Mobile experience: Verify text readability and layout integrity on smaller screens (like the iPhone SE).
- CTA functionality: Test all buttons and links across major clients, paying special attention to Outlook’s tendency to alter button rendering.
This step works hand-in-hand with email preview testing, providing the final visual pass before approvals.
5. Review, Approve, and Send
Once testing (manual or automated) is complete:
- The client receives a proof version—often as a Litmus or Email on Acid share link.
- Everyone reviews and comments in one shared space.
- After feedback and approvals, the campaign is ready to go live.
Everyone—designers, developers, QA, and clients—reviews the same tested version, eliminating last-minute surprises when the email reaches subscribers.
Final Thoughts on Email Template Testing
A flawless email campaign isn’t just about creativity or coding precision, it’s about control. By combining Litmus, Email on Acid, and the right automation for email testing, your team transforms testing from a tedious checkbox task into a proactive quality assurance system.
Every preview, every fix, and every automated check contributes to one goal: ensuring that what your audience sees is exactly what you intended.
The result? Confident launches, consistent client trust, and campaigns that look exceptional everywhere, from Outlook desktops to Android inboxes.
If you’re ready to streamline your QA process and build bulletproof email workflows, partner with Email Mavlers to bring precision and performance to every send. Let’s get started!