Introducing Mailgun Inspect, our powerful new email preview and QA platform fully integrated into the high-performance Mailgun Platform. Start QA testing.

Deliver more emails

Email testing tools for functional, flawless emails

Stop sending emails with broken links and images. Mailgun’s email testing tools ensure that every template you create looks and works as intended before ever impacting your deliverability.
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Flawless emails

Test and send emails with confidence

Make every email you send polished and flawless. With email testing tools by Mailgun Inspect, spot problems before subscribers see them so you skip spam folders and get the best results from your email campaigns.

  • Correct spammy content so emails land in inboxes, not spam traps
  • Spot broken links and validate emails across email clients and mobile devices
  • Optimize images for faster load times and rendering
  • Test subject lines  with a message header testing tool to improve open rates
  • Use tags to A/B email test button placement, design, CTAs, and more
Three email icons lined up diagonally.

Faster delivery

Image testing for clarity and design fit

Large or poorly sized images can drag down open times. With image validation, easily check that images are proportional and sized correctly for lightning-fast open times.

  • Set borders and widths so your images render perfectly in every device or client—every time
  • Built in pre-checks spot check images and formatting before email rendering to save you even more time
Inspect QA for image sizes

Smoother sends

Email client testing

Ensure subscribers see emails the way you intended. Test, preview, and update emails across devices, email clients, and applications so your message always displays properly.

  • Review and edit formatting across devices using conditional HTML for easy updates
  • Skip test accounts for every email provider. Preview, flag broken links, and test emails across 100+ email clients like Gmail, Microsoft Outlook, Apple Mail, and Yahoo
  • Preview emails across mobile devices. Scroll through your email previews across devices and pinpoint potential issues in the HTML code
Inspect email preview feature

Improved Email Delivery

Content Spam Testing

Prevent emails from landing in spam folders or being blocked altogether. Test your emails in an isolated environment, independent of sender reputation, against common spam filters to evaluate performance before sending. Analyze results across both B2B and B2C environments for a comprehensive view of content quality, so you can iterate with confidence.

Or take spam testing a step further with inbox placement (seed) testing to see how your messages are delivered across major ISPs and email clients, with sender reputation factored in. Gain clear insight into inbox, folder, spam, or blocked placement and improve deliverability with every send.

Spam trap monitoring dashboard

Use cases

Email testing tools for every team

Marketers

Improve email metrics with testing tools and improve results across platforms.

Developers

Run automated email tests and implement code changes directly through API.

Designers

Validate compliance and accessibility across device-ready email templates.

Email testing tools FAQ

An email testing tool allows you to preview, validate, and troubleshoot email campaigns before sending. These tools simulate how your emails render across devices, clients (e.g., Gmail, Outlook), and screen sizes. They also detect issues like broken links, accessibility problems, load times, and spam filter triggers—helping you ensure deliverability, design consistency, and optimal user experience.
Mailgun can detect issues such as spam triggers, broken HTML formatting, missing authentication (SPF, DKIM, DMARC), and inconsistent rendering across different email clients.
Testing ensures your emails display correctly across clients and devices, avoiding layout issues or broken functionality. It also helps catch deliverability problems, like spam triggers or domain authentication failures (DKIM, SPF, DMARC). Without testing, you risk losing credibility, conversions, or getting flagged by spam filters—especially in a fragmented email client ecosystem.
Yes, Mailgun’s testing software allows you to preview how your emails appear in various email clients, including Gmail, Outlook, Apple Mail, and mobile devices.
Yes, Mailgun supports both transactional and marketing emails, ensuring they are properly formatted, optimized, and compliant with email best practices.
Not testing your email can lead to inconsistent rendering, broken designs, and deliverability issues. Your email might look perfect in Gmail but completely fail in Outlook. Broken links, unreadable layouts, or failed authentication can reduce engagement and increase bounce rates. Worst case: your message lands in spam or damages your sender reputation.

Other features

Explore beyond email testing tools

Mailgun has a variety of features for companies in need of robust email testing tools.