Spent hours crafting the perfect cold email. The subject line is sharp, the copy is compelling, and the CTA is irresistible. You hit send—and then… crickets.
The culprit? Your email never reached the inbox.
In 2024, 47% of cold emails land in spam (HubSpot). For sales teams, that means wasted effort, lost leads, and crushed quotas. But deliverability isn’t luck—it’s science.
At SaleSix.AI, we’ve helped B2B, eCommerce, and financial service teams boost deliverability from 65% to 92%. Here’s your battle-tested playbook to avoid spam filters and reach real people.
(Psst—Pair these tactics with Agentic AI to automate and scale outreach without killing sender reputation.)
Why Emails Go to Spam (The 5 Biggest Triggers)
1. Poor Sender Reputation
- What It Is: Your “credit score” with email providers (Gmail, Outlook, etc.).
- Killer Factors:
- High bounce rates (>2%)
- Spam complaints (>0.1%)
- Low engagement (opens <15%)
Fix: Use Google Postmaster Tools to monitor reputation.
2. Missing Authentication
- New Rule (2024): Gmail/Yahoo require SPF, DKIM, and DMARC.
- What Happens Without It: Emails get blocked outright.
Quick Check: Run your domain through MXToolbox’s Deliverability Test.
3. Spammy Content
- High-Risk Words:Spam TriggerSafe Alternative“Free””Complimentary””Act now””Priority access””Guaranteed””Proven results”
AI tools like SaleSix.AI’s Email Optimizer auto-flag risky phrases.
4. Bad List Hygiene
- Sending to:
- Invalid emails (bounces)
- Inactive addresses (6+ months no opens)
- Purchased lists (#1 deliverability killer)
Fix: Scrub lists with ZeroBounce or Hunter.io.
5. Sudden Volume Spikes
- Example: Sending 5,000/day after averaging 50/day.
- Result: ESPs flag you as a spammer.
Rule: Increase volume by 20% daily during warm-up.
Step-by-Step Deliverability Fixes
1. Set Up Authentication (The Bare Minimum)
- SPF: Lists servers allowed to send for your domain.
- DKIM: Digitally signs emails to prove they’re legit.
- DMARC: Tells ESPs what to do with failed emails (monitor/reject).
How To: Follow your ESP’s guide (e.g., Gmail’s setup).
2. Warm Up Your Domain
- New Domain? Start with 20-50 emails/day, scaling over 4-6 weeks.
- Tools: Use Mailchimp’s Warm-Up or Lemlist’s AI Sender.
3. Optimize Engagement
- Best Practices:
- Send when opens peak (Tues-Thurs, 8-10 AM or 4-6 PM local time).
- A/B test subject lines (avoid ALL CAPS or excessive emojis).
- Prune non-openers every 30 days.
Data: Emails with >50% open rates get inbox priority (Return Path).
4. Monitor Blacklists
- Check If You’re Listed: MxToolbox Blacklist Check.
- If Blacklisted: Submit removal requests via Spamhaus or Barracuda.
Industry-Specific Tips
| Industry | Challenge | Solution |
|---|---|---|
| Finance | Strict spam filters | Use plain-text emails (no images) |
| eCommerce | Promo emails flagged | Add physical address in footer |
| Healthcare | HIPAA compliance | Encrypt PHI emails (Paubox) |
Case Study: From 12% to 89% Inboxing
Company: B2B SaaS (CRM)
- Problem: 88% of emails went to spam.
- Changes Made:
- Fixed DKIM misconfiguration.
- Scrapped purchased lists (built organically via LinkedIn).
- Added 2-line personalized intros.
- Result: 89% deliverability in 60 days.
When All Else Fails…
- Try a New Domain: Fresh domains have “neutral” reputations.
- Switch ESPs: Move from shared IPs (Mailchimp) to dedicated IPs (SendGrid).
- Go Multi-Channel: Pair emails with AI voice calls (like SaleSix.AI) for backup.
Deliverability Is a System, Not a Hack
Landing in the inbox requires technical setup, behavioral discipline, and constant monitoring. Treat your sender reputation like your credit score—nurture it, and it’ll open doors.
