Migrate from Email on Acid to Mailgun Inspect

This guide helps you transition from Email on Acid (EoA) to Inspect with minimal disruption to your workflow.

NOTE: If you were exclusively an API user, you should consult our API documentation instead.

What Stays the Same

• Email previews across major clients and devices
• Ability to test HTML before sending
• Core QA checks (links, images, formatting)
• Spam testing

What's Changing

• Faster, simplified test setup - Inspect is optimized for a fast test → review → fix → re-test workflow.
• No more Campaign Pre-check - all QA features are rolled into one, simplified workflow.
• Removal of the Analytics feature - Inspect is purely focused on previews and pre-send QA.
• New development coming in 2026 - code editor, ESP integrations, iOS previews, and more assistance for fixing issues.
• Allotments - no more unlimited previews, but now there are unlimited users.

Recreate Your Workflow

Upload Your Email

Inspect has the same upload features as Email on Acid, other than upload via Zip File:

• Send in from ESP
• Paste HTML
• Upload URL containing HTML

Best practice: Use the same method you used in EoA to reduce friction.

Run a Test

1. Upload your HTML (or send it in via ESP)
2. Select your target email clients
3. Run the test

This should be identical to your Email on Acid workflow.

Review Results

Inspect organizes results into four areas:

1. Previews
   • Visual rendering across clients and devices
   • Focus on layout, mobile, and dark mode issues
2. Fix Issues
   • Broken links
   • Missing images
   • Accessibility flags
3. Code Analysis
   • Highlights issues where your HTML may not be supported by certain providers
4. Spam Check
   • Checks if your content will have any deliverability issues for major mailbox providers or spam filters

Fix and Re-Test

Make updates in your ESP or code editor, then re-run your test. This should be identical to your Email on Acid workflow.

Inspect does not support full in-app HTML editing, but that functionality will be coming in 2026.

Known Differences

Spam Testing

Spam testing in Inspect only offers the option where your HTML is sent from our IPs - you do not have the option to send in a spam test from your own IPs. This is intentional and is meant to isolate the deliverability signal to your content. If you are interested in inbox placement testing where you send your email to a seed list from your own IPs, check out Mailgun Optimize.

Campaign Pre-check

If you used "Campaign Pre-check" in Email on Acid, the workflow will be slightly different. Instead of walking through the QA checks during test submission, all tests will be run at once, and you can find link, image, and accessibility information on the Fix Issues tab.

Code Editor

Inspect does not have a code editor today, but it will be added later this year. The code editor in Inspect will be much more integrated into the preview, QA, and fixing issues workflow than the code editor from Email on Acid.

For now, you can continue to make updates in your ESP or 3rd party code editor.

Collaboration

Commenting and flagging for problematic previews is not currently in Inspect, but will be added later this year.

A common workaround is to take screenshots of problem previews and communicate about them via a messenger or Jira.

Analytics

The pixel will not be brought into Inspect, as Inspect is entirely focused on pre-send testing workflows.

When to Reach Out

Contact support if:

• A critical preview is missing
• Results in the Fix Issues or Code Analysis tabs are missing or incorrect
• A missing feature blocks the previewing workflow