SPF, DKIM and DMARC are three small records you add to your domain's DNS. Together they let Gmail, Outlook and Yahoo check that an email claiming to be from your domain really is. Without them, your mail is far more likely to land in spam, or not arrive at all.
What each one does
- SPF lists the servers allowed to send email for your domain. It's a TXT record that looks like
v=spf1 include:_spf.google.com ~all. - DKIM adds a digital signature to every email. The receiving server checks it against a public key in your DNS, which proves the email wasn't changed on the way.
- DMARC tells receiving servers what to do when SPF or DKIM fails, and sends you reports. A safe starting record is
v=DMARC1; p=none; rua=mailto:you@yourdomain.com.
Why it matters more now
Gmail and Yahoo introduced rules for bulk senders in 2024, and Gmail started actively rejecting non-compliant mail in November 2025. If you send around 5,000 or more emails a day to Gmail addresses, you need:
- SPF and DKIM, plus a DMARC record that aligns with your From address
- A one-click unsubscribe link in marketing emails
- A spam complaint rate below 0.3% (aim for under 0.1%)
Smaller senders aren't held to every rule, but having SPF, DKIM and DMARC in place helps anyone's deliverability.
How to set them up
- Find the SPF and DKIM values in your email provider's settings (Google Workspace, Microsoft 365, your SMTP host, etc.).
- Add them as TXT records at your domain registrar or DNS host (Cloudflare, Namecheap, GoDaddy…).
- Add a DMARC record at
_dmarc.yourdomain.com, starting withp=none. - Send a test email to a Gmail address, open it, click Show original and check that SPF, DKIM and DMARC all say PASS.
- After a few weeks of clean reports, tighten DMARC to
p=quarantine.
Once your records pass, warm up the domain before sending at volume.