Email testing tools are an essential part of any successful email marketing strategy. They allow you to preview, test, and optimize your emails before sending them to ensure they look great and perform well across a wide range of devices, email clients, and browsers. In this comprehensive guide, we'll take an in-depth look at the top email testing platforms, comparing their features and best use cases to help you choose the right tool for your needs.
The following diagram provides an overview of the key components and workflow of a typical email testing process:
Why Email Testing Matters
Email testing is crucial for several reasons:
- Ensure Deliverability: Testing helps identify potential spam triggers or technical issues that could prevent your emails from reaching subscribers' inboxes.
- Optimize Rendering: With the wide variety of devices, email clients, and browsers in use today, testing ensures your emails look great and function properly for all recipients.
- Improve Engagement: By previewing and refining your email content, layout, and design, you can create more compelling and effective emails that drive higher engagement rates.
- Protect Your Reputation: Sending broken or spammy emails can damage your sender reputation and future deliverability. Testing helps catch these issues before they impact your audience.
Key Features to Look for in Email Testing Tools
When evaluating email testing platforms, consider the following key features:
- Previews Across Devices/Clients: Look for tools that generate previews of how your email will render across a wide range of popular devices, email clients, and browsers.
- Spam Testing: Check if the platform can scan your emails for potential spam triggers and provide recommendations to improve deliverability.
- Link and Image Validation: Ensure the tool can verify all links and images in your email are working properly.
- Collaborative Workflow: For teams, look for features like live editing, commenting, and approval flows to streamline the email review process.
- Integrations: Consider how well the tool integrates with your existing email service provider and other key tools in your workflow.
Pro Tip: Test Early and Often
Don't wait until your email is ready to send to start testing. Test early in the design process and at multiple points along the way to catch and fix issues as quickly as possible.
Top Email Testing Tools Compared
Let's take a closer look at some of the most popular and full-featured email testing tools available today.
Litmus
Litmus (owned by Validity since 2025 and now part of Validity Engage) is one of the most powerful and comprehensive email testing platforms on the market. It offers an extensive set of features for previewing, testing, and collaborating on emails.
Key Features
- Previews across a wide range of email clients and devices
- Spam testing and scoring
- Link and image validation
- Collaborative email workflow and approvals
- Integrations with top email service providers
Pros
- Comprehensive previews and testing
- Powerful workflow and collaboration features
- Extensive integrations with ESPs and other tools
Cons
- Typically priced higher than most alternatives
- Can have a steeper learning curve
Best For
Litmus is best for larger teams and organizations that send a high volume of email campaigns. It's ideal for those that want access to the most comprehensive set of testing features and value advanced collaboration workflows.
Email on Acid
Email on Acid (now being replaced by Sinch's Mailgun Inspect, with customers moving across from June 2026) is another top email testing platform that offers a robust set of previewing, testing, and editing tools at a more affordable price point than Litmus.
Key Features
- Previews across a wide range of email clients and devices
- Spam testing and scoring
- Link and image validation
- Email editing and collaboration tools
- Workflow automation with auto-process testing
Pros
- Comprehensive previews and testing at a lower cost than Litmus
- Email editing features included
- Automated testing workflows available
Cons
- Fewer integrations than Litmus
- Some advanced collaboration features missing
Best For
Email on Acid is a great choice for small to midsize companies that want access to comprehensive email testing and editing tools at a more affordable price than the top-tier platforms. It's also well-suited for teams looking to automate parts of their testing workflow.
| Tool | Key Features | Best For |
|---|---|---|
| Litmus |
|
Enterprise & high-volume senders |
| Email on Acid |
|
Small to midsize teams |
Other Email Testing Tools to Consider
In addition to Litmus and Email on Acid, there are a few other email testing tools worth mentioning:
- Mailtrap: A test email server that lets you preview emails in a virtual sandbox before sending.
- Mail-Tester: A quick online spam testing tool that scores your email for common spam signals.
- SpamBarometer: Send your email to a test address and get a report covering SpamAssassin score, SPF, DKIM and DMARC results, block list checks and content suggestions.
The following diagram provides a simple visual comparison of the key differences between the top email testing tools:
Implementing Email Testing In Your Workflow
Once you've chosen an email testing tool, it's important to implement it effectively in your email production workflow. Here are some best practices and tips to follow:
Before you start building an email, align with your team and stakeholders on the key criteria it needs to meet to be considered ready for sending - proper rendering, working links/images, spam score, etc. This helps avoid confusion or last-minute issues.
Don't wait until the email is completely built to start testing. Test individual sections or elements as they're developed to identify and fix issues early. Then do a final comprehensive test before sending.
Prioritize your testing based on the devices/clients your specific audience uses most. Use your email analytics to identify the most popular configurations and ensure a great experience on those.
Many email testing tools integrate directly with ESPs and other marketing platforms. Take advantage of these integrations to automate the testing process as much as possible and avoid manual steps.
Example Testing Workflow
Here's an example of how an email testing tool could fit into an optimized production workflow:
- Create email markup in your ESP or code editor
- Paste markup into testing tool for initial previews
- Make adjustments based on preview rendering issues
- Add content and test individual sections - links, images, etc.
- Send a test email and check spam score
- If issues found, troubleshoot & repeat steps 3-5
- Once approved, schedule or send final email
- Review post-send analytics for insights for future tests
Conclusion & Next Steps
Email testing is a critical component of any successful email marketing program. By catching and fixing issues before you hit send, you can ensure a better experience for subscribers, improve performance, and protect your sender reputation.
The right email testing tool can automate and greatly streamline the previewing and QA process. When choosing a platform, consider your team's specific needs and budget. Look for a tool that offers the right balance of previewing and collaboration features to fit your workflow.
Ready to get started with email testing? Here are a few next steps:
- Audit your current email production & QA process to identify inefficiencies or gaps in testing
- Create an RFP doc outlining your key requirements and priorities for an email testing tool
- Schedule demos of 2-3 email testing platforms that seem like the best fit
- Select a tool and implement into your email workflow, creating new SOPs as needed
- Continually test, learn, and optimize your process to improve email quality and team efficiency
With the right tool and approach, email testing can help you send better email, faster, with less effort. Use this guide as a starting point to find the best platform for your needs.