Sender Policy Framework (SPF) is an email authentication protocol designed to prevent email spoofing by allowing domain owners to specify which mail servers are authorized to send emails on behalf of their domain. SPF works by adding a DNS (Domain Name System) record to the domain’s DNS settings.
How SPF Works
Here’s how SPF typically works:
| DNS Record | The domain owner publishes an SPF record in the DNS, indicating the authorized mail servers for sending emails on behalf of their domain. |
| Incoming Email | When an email is received, the recipient’s mail server checks the SPF record of the sender’s domain to verify if the sending mail server is authorized to send emails for that domain. |
| Authentication | If the sending mail server is listed in the SPF record, the email is considered authentic. If the server is not listed or the SPF check fails, the recipient’s mail server may take actions based on the SPF policy, such as marking the email as suspicious or rejecting it. |
SPF helps prevent email forgery and protects against certain types of phishing attacks that rely on sending emails with forged sender addresses. It provides a mechanism for domain owners to declare which servers are legitimate sources for their emails, and receiving mail servers can use this information to assess the authenticity of incoming messages.
Like DomainKeys Identified Mail (DKIM), SPF is part of the broader set of email authentication mechanisms. Combining SPF with DKIM and DMARC (Domain-based Message Authentication, Reporting, and Conformance) provides a more comprehensive approach to email authentication, helping to enhance the security of email communications.