An email authentication protocol designed to prevent email spoofing and ensure that emails are sent from authorized servers. SPF allows domain owners to specify which mail servers are permitted to send emails on behalf of their domain by publishing SPF records in their Domain Name System (DNS) settings. When an email is received, the recipient’s mail server checks the SPF record of the sender’s domain to verify that the email was sent from an authorized IP address. If the email fails this check, it may be marked as suspicious or rejected. SPF helps improve email deliverability and protect against phishing and spam by verifying the legitimacy of the email sender.