Catch Email Disasters
Before They Cost You Money
Test your campaign in 60 seconds with professional-grade validation. No signup, no credit card - just instant peace of mind.
Try It Free
Test Your Campaign Right Now
Get instant feedback on your email campaign. No signup required.
Check your next campaign free
We read the email your ESP delivered and report the links, merge tags, headers and authentication results
No credit card required • First report in ~60 seconds • Expires in 24 hours
17 Checks
Never Send a Broken Email Again
From career-ending disasters to professional optimizations - we catch it all in 60 seconds.
Follow every link to its destination and flag the ones returning 404
Catch 'Hi {{FirstName}}' — tags that didn't resolve in the email your ESP sent
Check the unsubscribe header your ESP sent — present, well-formed, one-click
Report the SPF, DKIM and DMARC results the receiving server recorded
Flag link shorteners, IP-literal hosts, punycode and risky TLDs
Flag images over 1MB or slow to respond, which delay rendering on mobile
Ensure tracking parameters are properly formatted
Avoid spam trigger words and excessive punctuation
Check DOCTYPE, html/body structure and nesting depth in the HTML your ESP sent
Flag deep nesting and missing table-based layouts that raise rendering risk
Flag images with missing or generic alt text
Measure HTML payload size and link redirect latency that slow delivery
Identify the click-tracking domain your links resolve through and the open-tracking pixel your ESP injected
Flag emails that are mostly markup with little real text, a spam-filter signal
Make sure your preheader text enhances open rates
Flag insecure http:// links and images that trigger client security warnings
Ensure reply addresses are present, valid, and domain-aligned
How It Works
Email validation in 3 simple steps
No integrations. No setup. Just instant validation that saves your reputation.
- 1Enter Your Email
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Get your unique test address instantly. No signup, no credit card required.
- 2Send From Your ESP
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Use your ESP's "Send Test" button to send your campaign to the test address.
- 3Get Results in 60 Seconds
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Receive detailed analysis via email with actionable fixes for any issues found.
Works With Your Tools
Quick Start Guide for Popular ESPs
No matter which platform you use, testing is simple
Klaviyo
In your campaign editor, click "Send Test" → Paste your test address → Click "Send"
Mailchimp
Use "Preview and Test" → Enter test email address → Click "Send Test"
HubSpot
Click "Test Send" → Add your test address → Click "Confirm"
SendGrid
Use "Send Test" option → Enter test address → Click "Send"
Works with any ESP that can send test emails - Brevo, ConvertKit, ActiveCampaign, and more
From Real Scans
What We Find in Real Marketing Email
Not industry averages, not projections. We ran real campaigns from real brands through the same engine that will scan yours, and counted what came back. Based on 800+ real marketing emails from 89 brands, Oct 2025 – Jul 2026.
- Campaigns with a link that 404s
- 1 in 6
- Hard 404s only, not redirects or timeouts
- Missing or malformed unsubscribe header
- 8 in 10
- The most common compliance problem we see
- Issues found per campaign, on average
- 3.2
- Counting only genuine defects, not tracking pixels
- To validate your entire campaign
- 60 sec
- vs checking everything by hand
Frequently Asked Questions
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Yes! Get instant access to a test email address with no credit card required. Send your campaign and receive detailed results in about 60 seconds. It's the perfect way to see the value before committing to a plan.
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Your test address expires after 24 hours for security. This one-time preview shows you exactly what SendGuard can catch in your campaigns. To protect every campaign you send with permanent addresses and saved history, start a free trial of our paid plans.
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The free preview is great for seeing what we catch, but paid plans give you unlimited checks, permanent test addresses, saved campaign history, and API access — plus team seats and priority support on Growth plans and up. Never worry about email mistakes again - test every campaign before it goes out.
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SendGuard works with any email platform that can send test emails - Klaviyo, Mailchimp, HubSpot, SendGrid, Brevo, ConvertKit, ActiveCampaign, and many more. If your ESP has a 'Send Test' button, it works with SendGuard.
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The preview runs the same engine as our paid plans — 17 checks covering everything from broken links and authentication to accessibility and mobile-render risks. Nothing is held back or simplified for the free version; the only difference is how many campaigns you can check and how long results are kept.
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Manual checking is slow and you'll still miss things. SendGuard runs 17 automated checks in 60 seconds, catching issues humans overlook - like broken authentication, accessibility problems, and mobile-render risks. One missed error can cost thousands in lost revenue.
Is the preview check really free?
What happens after 24 hours?
Why should I upgrade to a paid plan?
Which email platforms does this work with?
How accurate are the checks?
What makes SendGuard different from manual checking?
Ready for Unlimited Campaign Testing?
Start your 7-day free trial and test every campaign with confidence. No credit card required.