Sending a broken email damages your brand and wastes your marketing spend. This comprehensive checklist ensures every email you send is perfect—from rendering to deliverability.
Before You Start: Setup Checklist
- ☐ Email code is complete and final
- ☐ All placeholder content replaced
- ☐ Test data/merge tags ready
- ☐ Testing tools open (Mailglass Lite recommended)
1. Content Checklist
Copy
- ☐ Subject line is compelling and accurate
- ☐ Preheader text is set (not "View in browser")
- ☐ Spelling and grammar checked
- ☐ No placeholder text remaining (Lorem ipsum, [NAME], etc.)
- ☐ Personalization tags work correctly
- ☐ CTAs are clear and actionable
- ☐ Legal disclaimers present if required
Images
- ☐ All images load correctly
- ☐ Images are optimized (under 1MB total)
- ☐ Alt text on every image
- ☐ Decorative images have empty alt=""
- ☐ Images make sense without loading
- ☐ Retina images provided (2x) where needed
Links
- ☐ All links work (no 404s)
- ☐ Links go to correct destinations
- ☐ UTM tracking parameters present
- ☐ Unsubscribe link works
- ☐ View in browser link works (if present)
- ☐ Social media links correct
- ☐ No "javascript:" or "file://" links
2. Rendering Checklist
Desktop Clients
- ☐ Outlook 2016/2019/365 (Windows)
- ☐ Outlook for Mac
- ☐ Apple Mail
- ☐ Thunderbird
Web Clients
- ☐ Gmail
- ☐ Outlook.com
- ☐ Yahoo Mail
- ☐ AOL Mail
Mobile Clients
- ☐ iOS Mail
- ☐ Gmail app (iOS)
- ☐ Gmail app (Android)
- ☐ Outlook app (iOS/Android)
- ☐ Samsung Mail
Responsive Testing
- ☐ Desktop width (800px+)
- ☐ Tablet width (768px)
- ☐ Mobile width (375px)
- ☐ Columns stack correctly
- ☐ Text is readable without zooming
- ☐ Buttons are tappable (44x44px min)
3. Technical Checklist
HTML Quality
- ☐ HTML validates (no errors)
- ☐ All tags properly closed
- ☐ Tables have role="presentation"
- ☐ Styles are inlined
- ☐ No external CSS files
- ☐ DOCTYPE present
Outlook Compatibility
- ☐ MSO conditionals present where needed
- ☐ VML backgrounds work
- ☐ Fixed-width wrappers for max-width
- ☐ No CSS border-radius without VML fallback
- ☐ DPI scaling meta present
Dark Mode
- ☐ Logo visible on dark backgrounds
- ☐ Text colors adapt appropriately
- ☐ Images have backgrounds if needed
- ☐ meta color-scheme present
- ☐ Tested in Apple Mail dark mode
- ☐ Tested in Outlook.com dark mode
4. Accessibility Checklist
- ☐ lang attribute on <html> tag
- ☐ Alt text is descriptive (not just "image")
- ☐ Color contrast meets WCAG AA (4.5:1)
- ☐ Font size minimum 14px for body
- ☐ Link text is descriptive (not "click here")
- ☐ Layout tables have role="presentation"
- ☐ Logical reading order
- ☐ No color-only meaning
5. Deliverability Checklist
Content
- ☐ No spam trigger words in subject
- ☐ Good text-to-image ratio (60/40+)
- ☐ Physical address included
- ☐ Unsubscribe mechanism works
- ☐ File size under 102KB
Technical
- ☐ From domain matches authentication
- ☐ List-Unsubscribe header set
- ☐ No broken links
- ☐ No URL shorteners
Testing
- ☐ Send test to Gmail
- ☐ Send test to Outlook.com
- ☐ Check spam score (mail-tester.com)
- ☐ Verify not in spam folder
6. Send Test Email Checklist
- ☐ Test email sent to yourself
- ☐ Test email sent to team for review
- ☐ Test on multiple devices
- ☐ Merge tags render correctly
- ☐ Dynamic content shows right variants
- ☐ Schedule time is correct (check timezone)
- ☐ Recipient list is correct
7. Pre-Send Final Checks
- ☐ Campaign name is descriptive
- ☐ Subject line is final
- ☐ From name and email correct
- ☐ Reply-to address set
- ☐ Correct audience/list selected
- ☐ A/B test set up correctly (if applicable)
- ☐ Schedule confirmed
- ☐ Someone else has reviewed
Quick Reference: Priority Checks
If you're short on time, these are the must-do checks:
- Subject line and preheader - First thing recipients see
- Links work - Broken links = lost conversions
- Renders in Outlook - Largest corporate email client
- Mobile responsive - 60%+ opens are mobile
- Unsubscribe works - Legal requirement
- Not in spam - Send test to yourself first
Using Mailglass Lite for Testing
Mailglass Lite automates many of these checks:
- ✅ HTML validation with actionable fixes
- ✅ Outlook compatibility warnings
- ✅ Dark mode preview
- ✅ Desktop/tablet/mobile preview
- ✅ Accessibility checks
- ✅ Auto-fix for common issues
- ✅ Send test email to any address
Downloadable Checklist
Save this checklist as a bookmark or print it out. Use it before every send:
EMAIL TESTING CHECKLIST - 2026
□ Content
□ Subject line final
□ Preheader set
□ Spelling checked
□ All links work
□ Images load with alt text
□ Rendering
□ Outlook desktop
□ Gmail
□ Mobile (iOS/Android)
□ Technical
□ HTML validates
□ Under 102KB
□ Dark mode works
□ Accessibility
□ lang attribute
□ Color contrast
□ Readable fonts
□ Final
□ Test email sent
□ Peer review done
□ Ready to send!Key Takeaways
- Use a checklist for every send—don't rely on memory
- Prioritize high-impact checks when short on time
- Always send test emails before the real send
- Automate checks with tools like Mailglass Lite
- Get a second pair of eyes on important campaigns
Ready to test your emails? Try Mailglass Lite for comprehensive email testing and validation.