How to prevent email spoofing

Email spoofing happens when someone sends a message that appears to come from your domain. The strongest domain-level defense is a combination of SPF, DKIM, and DMARC enforcement.

SPF limits which servers can send. DKIM signs messages so receivers can verify they were not altered. DMARC ties those checks to the visible From domain and tells receivers what to do when mail fails.

A DMARC policy of p=none gives visibility but does not stop spoofed mail. To prevent impersonation at scale, domains should work toward quarantine or reject after legitimate senders are aligned.

Do not jump straight to reject without reports unless you are certain every sender is configured correctly. A staged rollout prevents accidental disruption to billing, support, marketing, and product email.

Spoofing protection is not a one-time DNS task. Vendors change, DNS records drift, and new sending tools appear. Continuous monitoring catches missing records, relaxed policies, and authentication failures before attackers or mailbox providers do.

Also review inbound security signals such as MX configuration and STARTTLS support. They do not replace DMARC, but they help maintain a stronger email security posture overall.