Email is an essential communication tool, but it can be misused for spam, phishing, and spoofing. To protect against these threats, three key email authentication protocols are used: SPF, DKIM, and DMARC.
SPF (Sender Policy Framework)
Purpose: Verifies that an email is sent from an authorized server.
How it works: A domain owner publishes an SPF record in DNS listing the servers allowed to send emails for that domain. When an email is received, the recipient’s server checks this list.
Why it matters: Helps prevent email spoofing and improves the chances that legitimate emails are delivered successfully.
DKIM (DomainKeys Identified Mail)
Purpose: Ensures the email content hasn’t been altered and confirms the sender’s identity.
How it works: The sender’s server adds a digital signature to the email header using a private key. The recipient’s server uses a public key (published in DNS) to verify the signature.
Why it matters: Protects against tampering and builds trust in the sender’s domain.
DMARC (Domain-based Message Authentication, Reporting, and Conformance)
Purpose: Provides instructions on how to handle emails that fail SPF or DKIM checks.
How it works: A domain owner sets a DMARC policy in DNS that tells receiving servers to take one of three actions—none, quarantine, or reject—when an email fails authentication. It also enables reporting.
Why it matters: Prevents spoofing, improves email deliverability, and gives domain owners visibility into how their domain is being used
Why Use All Three?
SPF checks if the email is from an approved server.
DKIM verifies the message hasn’t been changed.
DMARC enforces rules and provides feedback.
Together, they form a strong defense against email-based threats and help ensure safe, reliable communication—especially important for schools and educational institutions.
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