Email authentication is a method to verify if the received email is from a legitimate source or is potential spam.

When an email is delivered, the receiving mail server uses a set of methods to determine if the message was sent from the person whose email address is specified in the From field. The receiving server also determines whether the received email was altered during transit. An email is rejected or marked as spam if the authentication fails. This protects the recipient from spoofing and phishing scams, where an email appears to have been sent from a legitimate sender but is actually sent by a malicious third party.

The following describes some of the most popular email authentication protocols available:

• Sender Policy Framework (SPF)

SPF is an open, Domain Name System (DNS) email authentication system that verifies that the email was sent from an authorized IP address. SPF is a record of the list of IP addresses (mail servers) that are authorized to send emails from a given domain. When an email is delivered, the receiving server uses the SPF record to check that the sender's IP address is in the list of authorized addresses. If there is a match, the email is sent to the receiver's inbox; otherwise, the incoming email is discarded.

• Domain Keys Identified Mail (DKIM)

DKIM verifies that the content in the incoming email has not changed or been altered during transmission. In this protocol, a public key is generated and added to the domain's server along with the DKIM record. When an email is sent, a DKIM signature is created and added to the message header. The DKIM signature contains information, such as email headers and a body, encrypted with an individual private key. The receiving server, uses the public key from the sender's server to recreate the encrypted message and compares it with the received message. If there is a match, the server authenticates the email.

• Domain Message Authentication Reporting and Conformance (DMARC)

DMARC is a policy for handling emails that fail SPF or DKIM authentication. It tells the receiving server what to do when the server receives an email that appears to have been sent from your domain but fails the SPF and DKIM checks. DMARC allows you to set up a policy and generate email performance reports. These measures make DMARC the most reliable authentication tool against spoofing.

In the absence of email authentication, spammers can change the source address of emails and avoid spam filters and other defense mechanisms. Cybercriminals can send emails without authentication, copy the company's branding to match the original look and feel, and entice customers to click fraudulent websites where personal information is stored.

Email authentication acts as a digital identification that protects your brand and reputation. Therefore, configuring one or more authentication methods is crucial to protecting your company's security and reputation.