Why Deliverability Matters
Email deliverability is the foundation of every outbound campaign. If your emails land in spam, nothing else matters — not your copywriting, not your targeting, not your offer. This checklist covers everything you need to maximize inbox placement.
Pre-Launch Checklist
Domain Authentication
Before sending a single cold email, complete these authentication steps:
- **SPF (Sender Policy Framework)**: Add a TXT record to your DNS that specifies which mail servers are authorized to send email on behalf of your domain
- DKIM (DomainKeys Identified Mail): Enable DKIM signing through your email provider to cryptographically verify emails came from your domain
- DMARC (Domain-based Message Authentication): Set up a DMARC policy that tells receiving servers what to do with unauthenticated emails. Start with p=none for monitoring, then move to p=quarantine
- Custom tracking domain: Set up a custom domain for link tracking instead of using shared tracking domains
- Verify all records: Use tools like MXToolbox or Google Admin Toolbox to confirm all DNS records are properly configured
Infrastructure Setup
- **Dedicated sending domain**: Purchase a separate domain for cold outreach (e.g., if your main domain is company.com, use trycompany.com or getcompany.com)
- Multiple sending domains: Set up 2-3 sending domains to distribute volume and reduce risk
- Separate mailboxes: Create individual email accounts (not aliases) for each sender
- Warmup period: Plan for 2-4 weeks of gradual warmup before launching campaigns
- Warmup tool: Use an automated warmup service to build sender reputation with realistic email exchanges
- Daily sending limits: Start at 5 emails/day during warmup, gradually increase to 30-50/day per mailbox
Email Service Provider Configuration
- **SMTP settings**: Configure your sending platform with proper SMTP credentials
- Sending schedule: Set up sending windows during business hours (8am-6pm recipient timezone)
- Rate limiting: Configure delays between emails (minimum 60-90 seconds between sends)
- Reply handling: Ensure replies route to the correct inbox and are monitored
- Bounce handling: Configure automatic removal of hard bounces from future sends
Ongoing Monitoring Checklist
Daily Checks
- **Bounce rate**: Should be under 3%. Investigate immediately if it spikes above 5%
- Spam complaints: Monitor for any spam reports. Even 1-2 complaints per thousand emails is a warning sign
- Reply monitoring: Respond to all replies within 4 hours during business hours
- Warmup tool status: Ensure warmup emails are still flowing normally
Weekly Checks
- **Open rate trends**: Track week-over-week changes. A declining open rate often indicates deliverability issues
- Domain reputation: Check Google Postmaster Tools and Microsoft SNDS for reputation scores
- Blacklist check: Scan your sending IPs and domains against major blacklists (Spamhaus, Barracuda, etc.)
- Sending volume review: Ensure you haven't exceeded recommended daily limits
- Content analysis: Review any emails that generated spam complaints
Monthly Checks
- **Full DNS audit**: Re-verify SPF, DKIM, and DMARC records are intact and correct
- Domain health score: Use domain reputation tools to get an overall health assessment
- List hygiene: Clean your contact lists by removing bounces, unsubscribes, and non-engagers
- Infrastructure review: Assess whether you need additional sending domains or mailboxes
- Warmup reassessment: Determine if any mailboxes need re-warming after periods of inactivity
Content Best Practices
What to Avoid
- **Spam trigger words**: Minimize use of words like "free," "guarantee," "act now," "limited time"
- Excessive links: Keep to 1-2 links maximum per email
- Image-heavy emails: Use plain text or minimal formatting. Avoid images in cold outreach
- HTML formatting: Avoid heavy HTML templates. Plain text performs better
- Large attachments: Never include attachments in cold emails
- URL shorteners: Avoid bit.ly and similar services — they trigger spam filters
- ALL CAPS: Never use all-caps in subject lines or body copy
- Exclamation marks: Limit to zero or one per email
What to Include
- **Plain text format**: Simple, conversational emails that look like they were written by a real person
- Personalization tokens: Include the prospect's name, company, or other relevant details
- Clear sender identity: Use a real name, title, and company in your signature
- Unsubscribe option: Include a way for recipients to opt out (required by CAN-SPAM)
- Physical address: Include a physical mailing address in your signature
- Mobile-friendly formatting: Short paragraphs, 2-3 sentences each
Troubleshooting Common Issues
**Problem: Sudden drop in open rates**
- Check domain and IP reputation scores
- Scan blacklists for your sending domains
- Verify DNS records haven't been altered
- Review recent content changes that may have triggered filters
- Pause campaigns and re-warm if necessary
**Problem: High bounce rate**
- Verify your contact data source and quality
- Run email verification on your list before sending
- Remove role-based emails (info@, sales@, etc.)
- Check if your sending domain has been blacklisted
**Problem: Emails going to spam in Gmail**
- Check Google Postmaster Tools for domain reputation
- Reduce sending volume temporarily
- Improve engagement signals by targeting more responsive segments
- Review and simplify email content
**Problem: Emails going to spam in Outlook/Microsoft**
- Check Microsoft SNDS for IP reputation
- Submit your domain for Junk Mail Reporting Program (JMRP)
- Ensure proper authentication records
- Reduce links and formatting in emails
Key Takeaways
- Authentication (SPF, DKIM, DMARC) is non-negotiable — set it up before sending anything
- Use dedicated sending domains and never risk your primary domain
- Warmup is essential — rushing this step will damage your reputation
- Monitor deliverability daily and investigate any anomalies immediately
- Keep email content simple, personalized, and free of spam triggers
- Regular list hygiene prevents reputation damage from bad contacts