Works with Mailgun

Inbox Preview for Mailgun: Free Browser-Based Tool

Q: Is there a free way to cross-client email preview for Mailgun campaigns?

Yes. The MiN8T Inbox Preview below runs entirely in your browser — no signup, no upload, and the output works with any Mailgun workflow.

→ Open the free Inbox Preview

Browser-only, no signup, no upload. Output works with any Mailgun campaign.

Built by the MiN8T Engineering Team · Updated 28 May 2026

Mailgun's built-in tools cover the basics, but the inbox preview workflow often benefits from a dedicated, browser-only preprocessor before uploading. {ESP_NAME}'s built-in preview shows one rendering — usually their own webmail. Real cross-client testing means simulating Gmail Web, Apple Mail iOS, and Outlook desktop side-by-side before you send.

Why pre-process before uploading to Mailgun

Mailgun does not offer pre-send rule scoring. External free tools fill this gap.

Step-by-step: cross-client email preview for Mailgun

Paste your HTML email source into the free inbox preview tool below
See three side-by-side renderings: Gmail Web, Apple Mail iOS, and a strict-mode Outlook approximation
Identify cross-client failures (flexbox layouts that collapse in Outlook, custom fonts that fall back, dark-mode contrast issues)
Iterate before sending through Mailgun

Mailgun-specific deliverability quirks to know

Mailgun is API-first transactional + marketing. Pre-send hygiene scoring is essential since you control the HTML directly.

Frequently asked questions

Does Mailgun include a built-in inbox preview?

Mailgun provides basic functionality but lacks granular control. Mailgun does not offer pre-send rule scoring. External free tools fill this gap.

Is there a free way to cross-client email preview for Mailgun campaigns?

Yes. The free MiN8T Inbox Preview runs entirely in your browser — no signup, no upload, no rate limits. The output is a standard file you can upload directly to Mailgun.

What image size limit does Mailgun enforce?

Mailgun accepts uploads up to 5000 KB per image and recommends a max width of 600px for email body width. Supported formats: JPG, PNG, GIF, WebP.

Does Mailgun verify SPF, DKIM, and DMARC automatically?

Mailgun requires SPF and DKIM via DNS. DMARC monitoring is available on their Foundation plan and higher.

What about subject line analysis for Mailgun?

Mailgun does not offer subject line analysis. External tools provide it. Use the free subject line analyzer for length scoring, spam-trigger detection, and sentiment analysis before pasting into Mailgun.

Related free tools

While preparing your Mailgun campaign, you may also want:

Image Compressor — also free, browser-based, optimized for email marketers
GIF Compressor — also free, browser-based, optimized for email marketers
CSS Inliner — also free, browser-based, optimized for email marketers
Spam Score Checker — also free, browser-based, optimized for email marketers