Mailgun Inspect

About

Mailgun Inspect is a companion utility for Mailgun customers. It lets you take the email HTML you are currently working on in your browser and submit it to your own Mailgun Inspect account for:

• Cross-client previews — see how your email renders across a large catalogue of email clients (Gmail, Outlook, Apple Mail, mobile clients, dark-mode variants, and more) supported by Mailgun's preview rendering service.
• Link validation — flag broken links, missing URL schemes, and redirect issues.
• Image validation — flag missing images and oversized assets.
• Accessibility checks — surface WCAG-relevant issues with the offending HTML snippet and selector.
• Code analysis — HTML/CSS support reporting across email clients.
• Spam testing — request inbox-placement testing through Mailgun's spam testing service.

How it works
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1. You authenticate the extension with your own Mailgun API key. The key is stored in the browser's session storage, not on disk, and is cleared when the browser closes.
2. When you are working in a supported email editor or viewing email HTML in your browser, you click the extension icon (or the floating Mailgun beacon on the page) to open the Mailgun Inspect side panel.
3. You select which clients and which checks to run, then click "Run Preview". Only at that point does the extension extract the HTML of the email you are currently editing and submit it to your Mailgun account through the Mailgun API.
4. Results come back from your Mailgun account into the side panel. Clicking a flagged issue highlights the corresponding element on the page so you can fix it.

Supported environments
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The extension can extract email HTML from the email editor on the pages you are working on, including:

• Salesforce Marketing Cloud (Content Builder)
• Salesforce CRM email templates (Lightning)
• Mailchimp campaign editor
• Klaviyo template editor
• Constant Contact email editor
• Braze email composer
• BEE Free / BEE editor
• Mailviews
• Any other webpage, local HTML file, or .html file opened in the browser, via a generic HTML extraction fallback

These supported-environment names are used nominatively to describe where the extension recognises an email editor. Mailgun is not affiliated with, endorsed by, certified by, or in a formal integration with any of these third-party platforms. You are responsible for ensuring you have the right to extract and submit any content you choose to send to Mailgun Inspect.

Requirements
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• A Mailgun account with Inspect / Email Preview access.
• A Mailgun API key for that account.
• Chrome (or Chromium-based browser) supporting Manifest V3 and the Side Panel API.

Data handling, at a glance
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• The only data the extension extracts from your browser is the HTML content of the email you have explicitly chosen to send to Mailgun Inspect when you click "Run Preview".
• That HTML is sent directly from your browser to Mailgun's API (US or EU region, your choice) using your Mailgun API key. It is not sent to any third-party analytics, ad, or tracking service.
• Your API key is held in the browser's session storage only. It is cleared when the browser closes. The extension does not persist your API key to disk.
• The extension does not run in the background, does not read pages until you ask it to, does not collect browsing history, does not collect form inputs from unrelated pages, and does not transmit data to anyone other than Mailgun.
• See Mailgun's Privacy Policy and the extension's privacy disclosures (linked in the listing) for the full picture.

Your responsibilities as a user
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You are responsible for the content you submit to Mailgun Inspect and for having the rights and permissions to extract and submit that content. Do not use this extension to extract or submit content you do not have the right to use.

Support
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Use of Mailgun Inspect is governed by your existing Mailgun Terms of Service, Acceptable Use Policy, Privacy Policy, and (where applicable) Data Processing Addendum.

For support, contact Mailgun support through your Mailgun account. The Chrome Web Store listing is monitored by the Mailgun Inspect product team for bug reports and questions about the extension itself.