Email Authentication Explained: SPF, DKIM, and DMARC for Business

Email Authentication Explained: SPF, DKIM, and DMARC for Business Email spoofing remains one of the most effective attack vectors. Someone sends an email that appears to come from your CEO, your bank, or your IT department. Without proper authentication, there is no way to verify the sender. Three protocols work together to solve this: SPF, DKIM, and DMARC. At Nubo.Email, we implement all three and surface their results directly in the email interface. SPF (Sender Policy Framework) SPF answers one question: Is this server authorized to send email for this domain? Domain owners publish a DNS record listing which servers can send email on their behalf. When an email arrives, the receiving server checks if the sending server is on that list. If not, the email fails SPF. DKIM (DomainKeys Identified Mail) DKIM answers a different question: Was this email modified in transit? The sending server digitally signs the email with a private key. The receiving server verifies the signature using a