Cold Email Deliverability Checklist
50 technical requirements for consistent inbox placement in 2026
How to Use This Checklist
This checklist covers everything that affects cold email deliverability. Items marked [CRITICAL] must be completed before sending any cold email. Other items improve deliverability incrementally.
Complete each section in order. Skipping sections will cause deliverability failures.
1. Domain Authentication (Do First)
[CRITICAL] Register a sending domain you own and control
[CRITICAL] Set up SPF record pointing to your SMTP provider
[CRITICAL] Set up DKIM record with cryptographic key
[CRITICAL] Set up DMARC record (start with p=none)
Upgrade DMARC to p=quarantine after 2 weeks
Upgrade DMARC to p=reject after 4 weeks
Set up DKIM rotation schedule
Configure reverse DNS (PTR record) for sending IPs
Verify all DNS records propagate correctly
2. Infrastructure Setup
[CRITICAL] Obtain dedicated IPs (not shared)
[CRITICAL] Complete 28-day IP warmup program
[CRITICAL] Set up domain rotation pool (minimum 3 domains)
Configure ISP-aware bounce monitoring
Set up automatic IP rotation triggers
Configure volume throttling per ISP limits
Set up subdomains for different campaign types
Configure tracking domains for opens/clicks
Set up feedback loop (FBL) with ISPs
3. List Quality Requirements
[CRITICAL] Verify emails with SMTP validation before sending
[CRITICAL] Remove spam trap hits (pristine, recycled, typo)
[CRITICAL] Remove hard bounces immediately
Remove soft bounces after 3 retry attempts
Remove emails with complaint history
Check list against do-not-mail registry
Verify list age (no new addresses under 6 months old for cold)
Segment list by engagement history
Remove addresses with high complaint probability
4. Content Requirements
[CRITICAL] Include physical mailing address (CAN-SPAM)
[CRITICAL] Include visible unsubscribe link
Personalize subject line and body
Keep HTML to text ratio balanced
Avoid spam trigger phrases in subject
Limit links to 3-5 per email
Use descriptive link anchor text
Avoid excessive punctuation and caps
Include plain-text version of HTML emails
5. Sending Practices
Send during recipient timezone windows
Limit volume per IP per hour (Gmail: 2,000, Outlook: 5,000)
Avoid sudden volume spikes (max 20% increase daily)
Vary subject lines across campaigns
Vary email body content and length
Send follow-up sequences (3-5 emails)
Include reply CTA to boost engagement
Remove unsubscribes within 24 hours
Monitor and adjust based on engagement
6. Ongoing Monitoring
Monitor per-ISP delivery rates daily
Track bounce rates (alert: Gmail >0.3%, Outlook >0.7%)
Monitor complaint rates (alert: >0.1%)
Check IP reputation scores weekly
Monitor blacklist status (check daily during warmup)
Review engagement rates by ISP
Audit content against spam filter updates
Rotate IPs when thresholds approached
Document and learn from campaign performance