Sender Policy Framework (SPF) is an email authentication protocol that helps prevent email spoofing by allowing domain owners to specify which mail servers are authorized to send emails on their behalf. When an email is received, the recipient’s mail server checks the SPF record published in the sender’s domain DNS to verify if the message comes from an approved source. If the email fails this check, it can be marked as suspicious or rejected, helping reduce spam and phishing attempts. However, SPF alone cannot prevent all types of email-based attacks and is most effective when combined with other authentication methods.