Sender Policy Framework (SPF) is an email authentication system designed to prevent email spoofing, a technique commonly used in phishing attacks where a malicious actor impersonates a legitimate sender. SPF works by allowing domain owners to define which mail servers are authorized to send emails on behalf of their domain. This is done through DNS (Domain Name System) records, where the domain owner specifies a list of trusted IP addresses or mail servers. When an email is sent, the recipient’s email server can check the SPF record of the sending domain to verify whether the sender’s IP address is on the approved list. If it is, the email passes the SPF check. If it’s not, the email may be marked as suspicious or rejected. SPF helps ensure that only legitimate sources can send emails on behalf of a domain, thus reducing the risk of phishing attacks and spam.