SPF vs DKIM vs DMARC Explained for Cold Email Senders

SPF, DKIM, and DMARC are the three DNS records that tell mailbox providers your emails are legitimate. Missing or misconfigured authentication is one of the top reasons cold emails land in spam. Here's what each record does and how to set them up.

SPF (Sender Policy Framework)

SPF tells receiving servers which IP addresses are authorized to send email for your domain. Without SPF, anyone can spoof your domain. With AWS SES, your SPF record includes include:amazonses.com.

DKIM (DomainKeys Identified Mail)

DKIM adds a cryptographic signature to every email proving it wasn't tampered with in transit. AWS SES generates DKIM keys when you verify a domain — add the CNAME records to your DNS provider.

DMARC (Domain-based Message Authentication)

DMARC tells receiving servers what to do when SPF or DKIM checks fail. Start with p=none to monitor, then move to p=quarantine once authentication is stable. Never skip DMARC — Gmail and Outlook increasingly require it.

How to Verify Your Setup

Use LeadSnipper's email deliverability tool to validate all three records continuously. The domain health dashboard flags missing or misconfigured authentication before you send campaigns.

For AWS SES-specific setup, see our Amazon SES cold email setup guide or the original step-by-step SES tutorial.