The Sender Policy Framework (SPF) is an email authentication protocol designed to prevent email spoofing. It allows domain owners to specify which mail servers are permitted to send emails on their behalf. This is done by adding a specific DNS record that lists the authorized servers, helping to ensure that only legitimate emails are delivered to recipients. When an email is received, the recipient's mail server checks the SPF record of the sender's domain. If the sending server is listed in the SPF record, the email is more likely to be considered legitimate. This process helps improve email security and reduces the chances of phishing attacks.