.png)
A perfectly crafted message sent from a misconfigured domain ends up in the spam folder. Deliverability is the technical prerequisite for any cold email campaign. Here are the fundamentals you need to master.
SPF: Specify who can send emails on your behalf
SPF (Sender Policy Framework) is a DNS record that lists the servers authorized to send emails from your domain. Without SPF, anyone could theoretically send emails pretending to be you. Anti-spam filters recognize this and penalize domains without SPF.
Standard setup for Lemlist or Gmail: Add a TXT record to your DNS with the value provided by your email sending tool. You can verify this on mxtoolbox.com.
DKIM: Cryptographically Signing Each Email
DKIM (DomainKeys Identified Mail) adds a cryptographic signature to every email sent. This signature allows the receiving server to verify that the email has not been tampered with in transit and that it actually comes from an authorized sender.
Each email sending tool (Lemlist, Instantly, Brevo) provides a DKIM key to add as a DNS record. Setup takes 5 minutes. Validation can take up to 48 hours.
DMARC: Defining What to Do in Case of Failure
DMARC (Domain-based Message Authentication Reporting & Conformance) tells receiving servers what to do if an email fails SPF or DKIM validation: let it through, quarantine it, or reject it.
Recommended setup for beginners: v=DMARC1; p=none; rua=mailto:votre@email.fr. The p=none means that you collect the reports without rejecting failed emails. Once the configuration is stable, proceed to p=quarantine then p=reject.
Warm-up: Essential Before Increasing Intensity
A new domain has no reputation. Sending 200 emails on the very first day is a surefire way to end up in the spam folder. The warm-up process involves gradually increasing the volume over 4 to 6 weeks by sending emails that generate positive interactions (opens, replies, no spam reports).
Week 1: 10 emails per day. Week 2: 20 per day. Week 3: 35 per day. Week 4: 50 per day. Week 5: 75 per day. Week 6: 100 per day.
Automatic warm-up tools (Lemwarm, Mailreach, Warmbox) create a network of emails that open and reply to one another to build reputation. They run in parallel with actual campaigns.
Signs to Watch For
Open rate below 25%: likely a deliverability issue; check your DNS records and reputation score.
Bounce rate above 3%: Clean up the list immediately using an email verification tool (NeverBounce, ZeroBounce).
Spam complaint rate above 0.1%: content or targeting needs to be reviewed immediately.
To learn more about optimizing deliverability over time, the comprehensive guide to cold email deliverability covers all the advanced aspects. And to ensure that the technique supports a cohesive strategy, AI-enhanced prospecting channels show how cold email fits into a multichannel system.
