Cold Email Deliverability: The Complete Checklist

Why Deliverability Is Everything

You can write the perfect cold email, but it means nothing if it lands in spam. Deliverability is the foundation of successful cold email - get it right, and everything else becomes easier.

The Reality:

• Average cold email inbox placement: 45%
• Well-optimized campaigns: 85%+
• Poorly optimized campaigns: 10-20%

The Math: If you send 100 emails with 45% deliverability vs 85%:

• 45%: 45 emails seen → 20 opens → 2 replies
• 85%: 85 emails seen → 38 opens → 4 replies
• Double the results with the same list

Domain & Infrastructure Checklist

Domain Setup

• Using separate domains for cold email (not main brand)
• Domains registered for 1+ year
• 3-5 domains minimum for sending rotation
• Domains aged 2-4 weeks before sending
• Clean domain history (check archive.org)

DNS Configuration

• SPF record configured and passing
• DKIM enabled and signatures valid
• DMARC policy set (start with p=none)
• Custom tracking domain configured
• MX records pointing to correct provider

Mailbox Setup

• Using Google Workspace or Microsoft 365 (not free Gmail)
• Real name and profile photo set
• Professional email signature
• 2-3 mailboxes per domain
• Each mailbox warmed independently

Warmup Status

• Manual warmup completed (week 1)
• Automated warmup running 2+ weeks
• Warmup continuing alongside outreach
• Warmup volume: 30-50/day per mailbox

List Quality Checklist

Email Verification

• All emails verified before sending
• Verification done within 30 days of sending
• Catch-all addresses identified and handled
• Role-based addresses removed (info@, sales@)
• Disposable email addresses removed

Data Quality

• Target audience clearly defined
• ICP (Ideal Customer Profile) documented
• Job titles verified and relevant
• Company data accurate and current
• Contact recently active (social, website visits)

List Hygiene

• Bounced addresses removed immediately
• Unsubscribes processed within 24 hours
• Complaints tracked and addresses removed
• Duplicate entries removed
• Invalid formats caught (special characters)

Target Metrics:

• Bounce rate: Under 2%
• Catch-all rate: Under 20%
• Valid rate: Over 95%

Content & Sending Checklist

Email Content

• No spam trigger words (FREE, URGENT, etc.)
• No excessive capitalization
• No red or unusual fonts
• Limited links (1-2 maximum)
• Plain text or minimal HTML
• No attachments

Sending Patterns

• Sending during business hours (recipient timezone)
• Randomized send times (not all at once)
• Volume increased gradually (max 20%/week)
• Weekend sending reduced or paused
• Holiday schedules adjusted

Volume Management

• Max 50 emails/day per mailbox (warmed)
• Max 150 emails/day per domain
• Spread across multiple sending windows
• Reply handling accounted for

Monitoring Checklist

Daily Checks

• Bounce rates reviewed
• Spam complaints checked
• Reply rates monitored
• Send failures investigated
• Warmup health verified

Weekly Checks

• Blacklist scan (MXToolbox)
• Google Postmaster reviewed (Gmail reputation)
• Microsoft SNDS checked (Outlook reputation)
• Domain reputation trending
• Overall deliverability metrics

Monthly Checks

• Full domain health audit
• DNS records verification
• Warmup optimization review
• List quality assessment
• Platform performance comparison

Blacklist Prevention

Warning Signs

• Open rates dropping below 20%
• Sudden increase in bounces
• Replies mentioning spam folder
• Delivery delays increasing

If Blacklisted

1. Stop sending immediately
2. Identify the blacklist (MXToolbox)
3. Determine cause (complaints? trap hits?)
4. Request removal (follow blacklist process)
5. Fix underlying issue before resuming
6. Restart warmup from reduced volume

Major Blacklists to Monitor

• Spamhaus
• Barracuda
• SpamCop
• URIBL
• Proofpoint

Provider-Specific Tips

Gmail Recipients

• Google Postmaster Tools essential for monitoring
• Image-heavy emails flag spam filters
• High engagement improves future deliverability
• Reply rates matter more than opens

Outlook/Microsoft Recipients

• Microsoft SNDS for reputation data
• Avoid formatting complexity
• Subject line personalization helps
• Consistent sending IP preferred

Corporate Recipients

• May have additional spam filters (Barracuda, Proofpoint)
• Plain text often performs better
• Shorter emails pass filters more easily
• Domain age matters more

Recovery Protocol

If deliverability drops significantly:

Day 1-3:

1. Pause all cold outreach
2. Run blacklist checks
3. Verify DNS records still correct
4. Increase warmup to 100% of volume
5. Document timeline of changes

Day 4-7:

1. Continue warmup only
2. Monitor for improvement
3. Clean email lists
4. Review recent email content
5. Check for pattern triggers

Week 2:

1. Slowly reintroduce cold outreach
2. 25% of previous volume
3. Monitor closely
4. Adjust content if needed

Week 3-4:

1. Gradually increase if stable
2. Add 20% volume weekly
3. Continue elevated warmup
4. Maintain monitoring