What is Cold Email Deliverability?
Cold email deliverability is the percentage of your outbound emails that successfully reach recipients’ primary inboxes. It’s the foundation of any outbound sales program—if your emails land in spam, nothing else matters.
The math is simple:
- 1,000 emails sent with 90% deliverability = 900 potential conversations
- 1,000 emails sent with 30% deliverability = 300 potential conversations
A 60% difference in deliverability means 3x fewer opportunities.
The Three Pillars of Deliverability
1. Domain & Technical Setup
Before sending a single cold email, your technical foundation must be solid.
Use secondary domains:
Main domain: yourcompany.com (protect this)
Cold outreach: yourcompany.io, getyourcompany.com, tryyourcompany.comDNS records required:
| Record | Purpose | Example |
|---|---|---|
| SPF | Authorizes sending servers | v=spf1 include:_spf.google.com ~all |
| DKIM | Cryptographic email signing | Generated by email provider |
| DMARC | Policy for failed checks | v=DMARC1; p=none; rua=mailto:dmarc@yourcompany.com |
Verification checklist:
- Secondary domain purchased and connected to email provider
- SPF record configured
- DKIM enabled and verified
- DMARC policy set (start with p=none)
- Domain age: at least 2 weeks before warming
2. Email Warming
New domains have zero reputation. Email providers are suspicious of domains that suddenly start sending hundreds of emails.
The warming schedule:
| Week | Emails/Day | Focus |
|---|---|---|
| 1 | 5-10 | Personal conversations, replies |
| 2 | 15-25 | Mix of conversations and cold sends |
| 3 | 30-40 | Gradual cold email introduction |
| 4 | 50-100 | Full cold outreach volume |
Warming best practices:
- Use warming tools (Instantly, Warmbox, Lemwarm)
- Send to real contacts who will reply
- Mix positive replies, forwards, and mark-as-important actions
- Never skip warming—even 1 week helps
3. Sending Practices
Even with perfect setup, bad practices destroy deliverability.
Do this:
- Personalize every email (name, company, specific detail)
- Keep emails under 150 words
- Use plain text or minimal HTML
- Include unsubscribe link
- Send during business hours (recipient’s timezone)
- Space emails 3-5 minutes apart
Avoid this:
- Purchased email lists (high bounce rates)
- Attachments in first email
- Too many links (max 1-2)
- Spammy words (“free,” “guarantee,” “act now”)
- Sending from free email providers (Gmail, Yahoo)
- Volume spikes (consistent daily volume is key)
Key Metrics to Monitor
| Metric | Target | Action if Below |
|---|---|---|
| Open Rate | 40-60% | Check subject lines, deliverability |
| Bounce Rate | Under 2% | Verify emails before sending |
| Reply Rate | 5-15% | Improve personalization, offer |
| Spam Complaints | Under 0.1% | Better targeting, easy unsubscribe |
The Technical Deep Dive
SPF (Sender Policy Framework)
SPF tells receiving servers which servers are authorized to send email for your domain.
v=spf1 include:_spf.google.com include:servers.mcsv.net ~allv=spf1: Versioninclude:: Authorized senders~all: Soft fail for unauthorized (recommended)-all: Hard fail (stricter)
DKIM (DomainKeys Identified Mail)
DKIM adds a cryptographic signature to each email, proving it wasn’t modified in transit.
Your email provider generates this. Verify it’s working:
# Check DKIM record
dig txt selector._domainkey.yourdomain.comDMARC (Domain-based Message Authentication)
DMARC tells receivers what to do when SPF or DKIM fails.
v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.comStart with p=none (monitor only), then move to p=quarantine or p=reject after analyzing reports.
Common Deliverability Problems
Problem: Sudden drop in open rates
Causes:
- Domain reputation damaged
- IP blacklisted
- Content triggering spam filters
Solutions:
- Check blacklist status (MXToolbox)
- Reduce volume by 50% for 1 week
- Review recent email content for spam triggers
- Verify DNS records still valid
Problem: High bounce rates
Causes:
- Outdated email list
- Purchased/scraped data
- Catch-all domains bouncing
Solutions:
- Use email verification service (ZeroBounce, NeverBounce)
- Remove emails older than 6 months
- Implement real-time verification
Problem: Landing in promotions tab
Causes:
- HTML-heavy templates
- Too many images/links
- Marketing-style content
Solutions:
- Use plain text
- Write like a human, not a marketer
- Ask recipients to move to primary (increases sender reputation)
Tools We Recommend
| Tool | Purpose | Price |
|---|---|---|
| Instantly | Sending + warming | $37/mo |
| Lemlist | Sending + personalization | $59/mo |
| ZeroBounce | Email verification | $0.008/email |
| MXToolbox | DNS/blacklist checking | Free |
| Mail-tester | Email scoring | Free |
Key Takeaways
- Set up separate domains for cold outreach to protect your main domain
- Warm new domains for 2-4 weeks before scaling volume
- Keep bounce rates under 2% and spam complaints under 0.1%
- Personalization improves deliverability because it increases engagement
- Monitor metrics weekly and react quickly to drops
Need Help With Deliverability?
Setting up cold email infrastructure correctly takes time and expertise. We’ve helped dozens of companies build outreach systems that consistently land in the inbox.
Book a call to discuss your deliverability challenges.