SPF, DKIM and DMARC Explained for Non-Technical Marketers
6 min read
You do not need to be a sysadmin to understand why SPF, DKIM, and DMARC exist. These three DNS records are the authentication layer that tells the receiving mail server 'this email genuinely came from who it claims to be from.' Without them, your cold emails are more likely to land in spam or get rejected outright.
SPF: Saying Who Can Send on Your Behalf
Sender Policy Framework (SPF) is a DNS record that lists all the servers and services authorized to send email from your domain. If you use Google Workspace, Outlook, or a dedicated outreach tool, those services need to be included in your SPF record. When an email arrives claiming to be from yourdomain.com, the receiving server checks the SPF record. If the sending server is not on the list, the email may be rejected or marked as suspicious.
DKIM: Signing Your Emails
DomainKeys Identified Mail (DKIM) adds a cryptographic signature to your emails. Your sending server signs each outgoing email with a private key. The public key is published in your DNS records. When the receiving server gets your email, it looks up the public key, verifies the signature, and confirms the email was not modified in transit. This prevents tampering and impersonation.
DMARC: The Policy Layer
Domain-based Message Authentication, Reporting and Conformance (DMARC) tells receiving servers what to do when an email fails SPF or DKIM checks. The policy can be set to 'none' (just monitor), 'quarantine' (send to spam), or 'reject' (block entirely). DMARC also enables aggregate reports so you can see who is sending email on behalf of your domain.
How to Check Your Current Setup
- MXToolbox.com: paste your domain and check SPF, DKIM, and DMARC in seconds
- Google Admin Toolbox: useful if you're using Google Workspace
- Ask your IT team or domain registrar to walk through the DNS records with you
- Your email platform's setup guide: most tools include a checklist for authentication
What Happens If These Are Not Set Up
Emails sent without proper authentication are more likely to be flagged by spam filters, land in the promotions tab, or get blocked entirely by corporate mail servers. For cold outreach especially, authentication is not optional - it is the foundation that everything else relies on. Fix authentication before you worry about copy, subject lines, or personalization.