The Trust Trinity
Email was built without inherent security. To prevent spoofing and phishing, the industry developed three interconnected protocols that establish sender identity.
SPF (Sender Policy Framework)
SPF is a DNS record that lists the IP addresses authorized to send emails on behalf of your domain. Think of it as a guest list for your domain.
DKIM (DomainKeys Identified Mail)
DKIM adds a cryptographic signature to every email you send. It ensures the email wasn't tampered with in transit.
DMARC (Domain-based Message Authentication, Reporting, and Conformance)
DMARC ties SPF and DKIM together. It tells the receiving server what to do if an email fails authentication—whether to quarantine it or reject it entirely.