Email Deliverability Checklist: 35 Steps to Perfect Inbox Placement

Published February 10, 2026

Email deliverability isn't a single switch you flip—it's a system of interconnected best practices. Miss one critical element and your inbox placement rate plummets. This comprehensive checklist covers every aspect of email deliverability, from DNS records to content optimization.

📌 Update (2026): Check out our 2026 updated email deliverability checklist with new Gmail and Yahoo sender requirements.

I've organized this into 5 categories with actionable checkboxes you can use to audit your email program right now. Use this checklist before every major campaign and quarterly for maintenance.

Part 1: Authentication & Infrastructure (10 items)

Your technical foundation determines whether ISPs trust you. Get these wrong and nothing else matters.

☐ 1. SPF Record Configured

What it is: Sender Policy Framework tells receiving servers which IPs can send mail from your domain.

How to check:

nslookup -type=txt yourdomain.com

Should return:

v=spf1 include:_spf.google.com include:amazonses.com ~all

Action: Add to DNS: v=spf1 include:[your-esp] ~all

☐ 2. DKIM Signing Enabled

What it is: DomainKeys Identified Mail cryptographically signs your emails to prove authenticity.

How to check: Send test email to [email protected] and review the automated response.

Action: Generate DKIM keys in your ESP and add TXT record to DNS.

☐ 3. DMARC Policy Published

What it is: Domain-based Message Authentication tells receivers what to do when SPF/DKIM fail.

Recommended policy:

v=DMARC1; p=quarantine; rua=mailto:[email protected]; pct=100

Action: Start with p=none to collect data, then move to p=quarantine, then p=reject.

☐ 4. Reverse DNS (rDNS) Configured

What it is: Your sending IP should resolve back to your domain name.

How to check:

host your.sending.ip.address

Should return: mail.yourdomain.com

Action: Contact your hosting provider or ESP to set up PTR record.

☐ 5. Dedicated IP Address (for high volume)

When you need it: Sending 100,000+ emails/month or running time-sensitive campaigns.

Benefits:

• Full control over sender reputation
• Not affected by other senders on shared IPs
• Better for consistent, high-volume sending

Downside: Requires IP warmup (4-8 weeks) and consistent volume to maintain reputation.

☐ 6. IP Reputation Monitored

Where to check:

• Sender Score (aim for 90+)
• Barracuda Central
• MXToolbox Blacklist Check
• Cisco Talos

Action: Check weekly and immediately if deliverability drops.

☐ 7. Domain Reputation Monitored

Where to check:

• Google Postmaster Tools (Gmail reputation)
• Microsoft SNDS (Outlook reputation)
• Your ESP's reputation dashboard

Action: Set up automated alerts for reputation drops below "Medium."

☐ 8. Subdomain Strategy Implemented

Best practice: Send marketing emails from subdomain (mail.yourdomain.com) to protect root domain reputation.

Setup:

• Transactional: transact.yourdomain.com
• Marketing: mail.yourdomain.com
• Notifications: notify.yourdomain.com

Action: Configure separate authentication for each subdomain.

☐ 9. SSL/TLS Certificate Installed

What it does: Encrypts email transmission between servers.

How to check: Your ESP should show "TLS enabled" in settings.

Action: Modern ESPs enable this by default; verify in settings.

☐ 10. BIMI Record Published (Optional)

What it is: Brand Indicators for Message Identification displays your logo in Gmail/Yahoo inbox.

Requirements:

• DMARC policy at enforcement (p=quarantine or p=reject)
• Verified Mark Certificate (VMC) from DigiCert or Entrust
• Square SVG logo hosted on your domain

Action: Implement after DMARC enforcement is stable.

Part 2: List Hygiene & Management (8 items)

Your list quality is the single biggest factor in deliverability. A clean list trumps perfect technical setup every time.

☐ 11. Email Validation at Signup

Implementation: See our email list cleaning guide for detailed validation strategies.

// Real-time validation API
fetch('https://api.emails-wipes.com/validate', {
  method: 'POST',
  headers: {'Authorization': 'Bearer YOUR_API_KEY'},
  body: JSON.stringify({email: userInput})
})
.then(r => r.json())
.then(data => {
  if (data.status === 'valid' && data.disposable === false) {
    // Accept signup
  } else {
    // Show error message
  }
});

Benefit: Prevent bad emails from entering your list (stops 15-30% of invalid signups).

☐ 12. Double Opt-In Implemented

Process:

1. User submits email address
2. Send confirmation email with unique link
3. User clicks link to confirm subscription
4. Welcome email sent to confirmed address

Benefit: Confirms address validity and user intent (reduces complaints by 90%+). Read our double opt-in vs single opt-in comparison to choose the right approach.

☐ 13. Hard Bounces Removed Immediately

Definition: Permanent delivery failures (invalid address, domain doesn't exist).

Action: Automatically suppress after first hard bounce. Never retry hard bounces. Learn more in our email bounce handling guide.

Target: Hard bounce rate under 0.5% for clean lists.

☐ 14. Soft Bounces Monitored & Removed

Definition: Temporary failures (mailbox full, server down).

Policy:

• Retry soft bounces 3 times over 72 hours
• If still bouncing after 3 attempts, treat as hard bounce
• Remove addresses with 3+ soft bounces in 30 days

☐ 15. Complaint Rate Below 0.1%

What is it: Percentage of recipients who click "Report Spam."

How to monitor:

• ESP dashboard (most ESPs track this)
• Google Postmaster Tools (Gmail complaints)
• Feedback loops from major ISPs

Target: Below 0.1% (1 complaint per 1,000 emails).

If exceeding: Review content, segmentation, and unsubscribe process immediately.

☐ 16. Inactive Subscribers Suppressed

Definition: No opens/clicks in 180+ days.

Process:

1. Day 180: Send re-engagement campaign ("We miss you!")
2. Day 195: Final chance email ("Click to stay subscribed")
3. Day 210: Suppress from all future sends

Impact: Suppressing 20-30% of inactive users can improve deliverability by 15-25%.

☐ 17. List Validation Run Quarterly

Why: Email addresses decay at 22.5% annually (new job, abandoned account, etc.).

Process:

1. Export full list
2. Run through bulk validation API
3. Remove invalid, catch-all (if low engagement), disposable
4. Flag risky/unknown addresses for monitoring

Expected results: Remove 5-15% of list as invalid on first quarterly check.

☐ 18. Unsubscribe Process Under 2 Clicks

Best practice: One-click unsubscribe (no login required).

Implementation:

• Prominent unsubscribe link in footer
• List-Unsubscribe header for Gmail/Yahoo one-click
• Confirmation page (don't require second confirmation)
• Process immediately (within seconds, not days)

Code example:

List-Unsubscribe: <mailto:[email protected]?subject=unsubscribe>,
 <https://yourdomain.com/unsub?token=abc123>
List-Unsubscribe-Post: List-Unsubscribe=One-Click

Part 3: Content & Design (7 items)

Even with perfect infrastructure and a clean list, spammy content kills deliverability.

☐ 19. Spam Score Below 5.0

Testing tools:

• Mail Tester (aim for 8/10+)
• Litmus Spam Testing
• Your ESP's built-in spam checker

Test before every campaign, especially new templates.

☐ 20. Text-to-Image Ratio 60:40 or Better

Why: Image-only emails scream spam to content filters.

Best practice:

• At least 500 characters of text
• Images should supplement text, not replace it
• Always include alt text on images
• Test with images blocked

☐ 21. Spam Trigger Words Minimized

High-risk words to avoid:

• FREE, ACT NOW, URGENT, LIMITED TIME
• $$$, 100% free, Click here, Congratulations
• Winner, Prize, Cash, Guarantee
• Remove, Opt-in now, Dear friend

Not banned, just risky: Use sparingly and never in subject lines.

☐ 22. Subject Line Best Practices

Do:

• Keep under 50 characters (mobile truncates at ~40)
• Use personalization tokens ({firstName})
• Create curiosity or urgency (without spam words)
• A/B test everything

Don't:

• Use ALL CAPS or excessive punctuation!!!
• Mislead (subject must match content)
• Start with "Re:" or "Fwd:" unless it's a reply
• Use emoji excessively (1-2 max)

☐ 23. Links Properly Formatted

Best practices:

• Use your own domain for all links (not bit.ly or other shorteners)
• Limit to 3-5 links per email
• Ensure all links work (broken links = spam signal)
• Use HTTPS for all links
• Match visible text to destination (<a href="example.com">example.com</a>)

☐ 24. Personalization Tokens Working

Test all merge tags before sending:

• {firstName} → displays actual name, not blank or token
• {company} → has fallback value if empty
• {custom_field} → validated against your CRM data

Fallback example:

Hi {firstName|there},  // "Hi Sarah" or "Hi there"

☐ 25. Mobile-Responsive Design

Why: 60%+ of emails opened on mobile devices.

Checklist:

• Single-column layout for body content
• Minimum 14px font size
• Touch-friendly buttons (44x44px minimum)
• Test on iOS Mail, Gmail app, Outlook mobile

Part 4: Sending Behavior (6 items)

How you send is as important as what you send. ISPs watch sending patterns closely.

☐ 26. Consistent Sending Frequency

Why: Sudden volume spikes = spam flag.

Best practice:

• Send at roughly same volume each week
• If increasing volume, ramp gradually (10-20% per week)
• Don't go dark for weeks then blast 100k emails

Example weekly pattern: Mon 10k, Wed 10k, Fri 8k = consistent

☐ 27. Engagement-Based Throttling

Strategy: Send to most engaged users first, then gradually expand to less engaged.

Implementation:

1. Hour 0: Send to users who opened last 3 campaigns (highest engagement)
2. Hour 2: Send to users who opened 1-2 of last 3
3. Hour 6: Send to users who opened last 30 days
4. Hour 12: Send to remainder (if engagement still healthy)

Why it works: Early positive engagement signals to ISPs that your email is wanted.

☐ 28. IP Warmup Completed (for new IPs)

Schedule:

Critical: Monitor bounce/complaint rates at each step. If either spikes, pause and troubleshoot.

☐ 29. Sunset Policy Enforced

Definition: Automatic removal of chronically unengaged subscribers.

Policy example:

• 180 days no engagement → Re-engagement campaign #1
• 210 days no engagement → Re-engagement campaign #2 (final)
• 240 days no engagement → Auto-suppress from all sends

Exception: Recent subscribers (joined within 90 days) get longer grace period.

☐ 30. Send Time Optimization

Data to track:

• Open rate by send time
• Click rate by send time
• Engagement by day of week

General best times (B2C):

• Tuesday-Thursday, 10am-2pm local time
• Saturday morning (8-11am) for certain niches

Action: Use your own data to find optimal windows. Test and iterate.

☐ 31. A/B Testing Program Active

Test systematically:

• Week 1: Subject line variations (test 2-3 versions, 10% sample each)
• Week 2: From name (Company name vs. Person name)
• Week 3: Send time
• Week 4: Content variation

Measurement: Track open rate, click rate, and conversion rate. Winner rolls to full list.

Part 5: Monitoring & Maintenance (4 items)

Deliverability isn't set-and-forget. Continuous monitoring catches problems before they escalate.

☐ 32. Inbox Placement Testing

Tools:

• GlockApps (inbox placement testing)
• Email on Acid (deliverability + rendering)
• Litmus (rendering + inbox placement)

Frequency: Test new templates and monthly for ongoing campaigns.

Benchmarks:

• 90%+ inbox placement = excellent
• 70-90% = needs improvement
• <70% = critical issue, pause and fix immediately

☐ 33. Feedback Loops Registered

What are they: ISPs notify you when users mark your email as spam.

Register with:

• AOL Feedback Loop
• Yahoo Complaint Feedback Loop
• Microsoft JMRP (Junk Mail Reporting Program)

Action on complaints: Immediately suppress complainers from future sends.

☐ 34. Metrics Dashboard Monitored Weekly

Key metrics to track:

Action: Set up automated alerts when any metric crosses warning threshold.

☐ 35. Quarterly Deliverability Audit

Review checklist:

1. Re-verify all DNS records (SPF, DKIM, DMARC)
2. Check IP/domain reputation across all monitoring services
3. Review and update suppression list
4. Run full list validation
5. Test inbox placement across major ISPs
6. Review complaint and bounce trends
7. Update unengaged subscriber segments
8. Review and refresh content templates
9. Audit A/B test results and implement winners
10. Check for any new ISP requirements or policy changes

Schedule: First week of each quarter (Jan, Apr, Jul, Oct).

Downloadable Checklist

Save this checklist for easy reference:

Common Mistakes That Kill Deliverability

Even with this checklist, avoid these critical errors:

1. Buying Email Lists

Never. Purchased lists are 90%+ invalid/unengaged. Guaranteed to destroy your reputation. See the true cost of a dirty email list.

2. Ignoring Bounces

Sending to addresses that have bounced multiple times signals to ISPs that you don't maintain your list.

3. Inconsistent Sending

Going silent for months then blasting 50k emails looks exactly like compromised account behavior.

4. Skipping Double Opt-In

Single opt-in saves a step but costs you in spam complaints and invalid addresses. Review when to use double opt-in.

5. Not Monitoring Metrics

Deliverability problems escalate fast. Weekly monitoring catches issues when they're still fixable.

6. Making Unsubscribe Hard

Hidden or multi-step unsubscribe = spam complaints. Make it easy or users will mark you as spam instead.

7. Neglecting Mobile

60%+ mobile open rate means mobile-broken emails fail with the majority of your audience.

Emergency Troubleshooting

If deliverability suddenly drops 30%+:

1. Check blacklists immediately (MXToolbox, Barracuda, Spamhaus)
2. Review last campaign for spam trigger content or technical errors
3. Check bounce/complaint rates for unusual spikes
4. Verify DNS records haven't expired or been modified
5. Test inbox placement to identify which ISPs are blocking
6. Pause sends until issue identified (continuing to send makes it worse)
7. Contact ESP support for assistance and reputation data

Recovery time: Minor issues can recover in 1-2 weeks. Major reputation damage can take 4-8 weeks of perfect behavior to repair.

Conclusion

Email deliverability is a system, not a single fix. Work through this 35-point checklist systematically, and you'll have better inbox placement than 90% of senders.

The three pillars—authentication, list hygiene, and sending behavior—work together. Perfect authentication won't save a dirty list. A clean list won't help if your content screams spam. Excellent content won't reach anyone if your infrastructure isn't trusted.

Start here:

1. Fix authentication (items 1-3) today
2. Implement real-time validation (item 11) this week
3. Start suppressing inactive users (item 16) this month
4. Set up monitoring dashboard (item 34) for ongoing maintenance

Run through this full checklist quarterly, and you'll maintain excellent deliverability for years to come.